Rsync on a 2 micro sd card unit combined as an luks encrypted LVM, on top fscrypt: Fscrypt seems to lock from time to time, how to avoid?

Hope anyone has a hint, if fscrypt which serves for me as a replacement for the error prone ecyryptfs for my backed up home folder (which is in a different PV group, luks encrypted,ecryptfs home folder):

+-----------------------------------+        +-----------------------------------+
   |          Source: Home             |        |         Destination: Backup       |
   |     (eCryptfs on Home Partition)  |        |     (fscrypt on Backup Partition) |
   +-----------------------------------+        +-----------------------------------+
                \|/               |                   ^         \|/
                 |                |___________________|          |
                 |              (rsync from Home to Backup)      | 
                 v                                               v
   +-----------------------------------+        +-----------------------------------+
   |   eCryptfs Layer (Home Folder)    |        | fscrypt Layer (BackupHome)        |
   +-----------------------------------+        +-----------------------------------+
   |       Home Partition              |        |       BackupHome Partition        |
   +-----------------------------------+        +-----------------------------------+   
   |   LVM Volume (Home)               |        |   LVM Volume (BackupHome)         |
   +-----------------------------------+        +-----------------------------------+ 
   |   LVM: PV Group (Main SSD)        |        |   LVM: PV Group (USB Stick)       |
   +-----------------------------------+        +-----------------------------------+   
   |   LUKS Encrypted (Main SSD)       |        |   LUKS Encrypted (µSD Slot 1)     |
   +-----------------------------------+        +-----------------------------------+ 
   |   Physical Layer (Main SSD)       |        |   LUKS Encrypted (µSD Slot 2)     |
   +-----------------------------------+        +-----------------------------------+
                 \|/                            |           Physical Layer          |
                  |                             +-----------------------------------+
                  |                                             \|/
   +-----------------------------------+        +-----------------------------------+
   | Physical Layer (4 TB SSD)         |        |   Physical Layer (USB Stick)      |
   | Dual Boot Windows/Linux (LVM)     |        |   Combined 2 x 1.5TB µSD with     |
   | LUKS LVM in part.6, part.5 /boot  |        |                                   |
   | (root, home, swap)in 3.1TB Volume |        |   LVM into 2.8TB Volume           |
   +-----------------------------------+        +-----------------------------------+

Now I want to backup my data with the following command:

rsync -avvh --inplace --size-only --info=progress2 /home/userXXX/  /backupHome/userXXX/

I got from time to time randomly different error messages like these (side info below the log):

[..]
testdaten/shrinkMpegxxDB.log
          9,02G   0%  117,23MB/s    0:01:13 (xfr#915, to-chk=655/497427)
testdaten/yyy.zzz/
testdaten/scripts/
rsync: [receiver] open "/backupHome/userXXX/testdaten/shrinkMpegxxDB.log" failed: Required key not available (126)
          9,02G   0%  117,23MB/s    0:01:13 (xfr#915, to-chk=0/497427)  

sent 9,04G bytes  received 42,04K bytes  121,37M bytes/sec
total size is 1,75T  speedup is 194,06
rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1338) [sender=3.2.7]


[..]

rsync: [generator] recv_generator: mkdir "/backupHome/userXXX/.config/menus" failed: Required key not available (126)
*** Skipping any contents from this failed directory ***
rsync: [generator] recv_generator: mkdir "/backupHome/xxxx/.config/mpv" failed: Required key not available (126)
*** Skipping any contents from this failed directory ***
rsync: [generator] recv_generator: mkdir "/backupHome/userXXX/.config/nautilus" failed: Required key not available (126)
*** Skipping any contents from this failed directory ***
rsync: [generator] recv_generator: mkdir "/backupHome/userXXX/.config/nemo" failed: Required key not available (126)
*** Skipping any contents from this failed directory ***
rsync: [generator] recv_generator: mkdir "/backupHome/userXXX/.config/nomacs" failed: Required key not available (126)
*** Skipping any contents from this failed directory ***
rsync: [generator] recv_generator: mkdir "/backupHome/userXXX/.config/procps" failed: Required key not available (126)
*** Skipping any contents from this failed directory ***
rsync: [generator] recv_generator: mkdir "/backupHome/userXXX/.config/pulse" failed: Required key not available (126)
*** Skipping any contents from this failed directory ***
rsync: [generator] recv_generator: mkdir "/backupHome/userXXX/.config/qimgv" failed: Required key not available (126)
*** Skipping any contents from this failed directory ***
rsync: [generator] recv_generator: mkdir "/backupHome/userXXX/.config/remmina" failed: Required key not available (126)
*** Skipping any contents from this failed directory ***
rsync: [generator] recv_generator: mkdir "/backupHome/userXXX/.config/simple-scan" failed: Required key not available (126)
*** Skipping any contents from this failed directory ***
rsync: [generator] recv_generator: mkdir "/backupHome/userXXX/.config/systemd" failed: Required key not available (126)
*** Skipping any contents from this failed directory ***
rsync: [generator] recv_generator: mkdir "/backupHome/userXXX/.config/teamviewer" failed: Required key not available (126)

[..]

        103,23M   0%    2,26MB/s    0:00:43 (xfr#1034, ir-chk=1028/476659)
[sender] expand file_list pointer array to 1024 bytes, did move
[sender] expand file_list pointer array to 1024 bytes, did move
[sender] expand file_list pointer array to 1024 bytes, did move
[sender] expand file_list pointer array to 1024 bytes, did move
[sender] expand file_list pointer array to 4096 bytes, did not move
[sender] expand file_list pointer array to 16384 bytes, did not move
[sender] expand file_list pointer array to 32768 bytes, did move
        103,23M   0%    2,24MB/s    0:00:44 (xfr#1034, ir-chk=2841/479500)
[..]
total: matches=0  hash_hits=0  false_alarms=0 data=103226155

sent 124,32M bytes  received 46,81M bytes  3,20M bytes/sec
total size is 1,75T  speedup is 10.254,91
rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1338) [sender=3.2.7]

The complete backup was 1,8 TB. With the first "chunk" of transmitted data, each time interrupted by an error, was 747 GB. File access was forbidden. I tried it with bash commands but failed in the same way, so it was related to fscrypt. Each Time I delocked the home again and again (after each cancellation), It works on. Because the USB Stick got very hot I cooled it down with some cooling ice from the fridge:

fscrypt unlock /backupHome/userXXX

So what is your ideas? My suggestions for the error cause: - device went too hot (after cooling down and again delocking it was transferring 1TB in one "chunk") - did I accidentally make a mistake in delocking the fscrypted backupHome folder? - Is the LUKS/LVM/2µSD config bind together in an µSD expansion usb Module problematic? I hope anyone can help here! [EDIT] According to @SteffenUlrich and my own assumptions it might point strongly to HW issue due to - SD maybe does not comply well with ext4fs, mainly and only supports FAT/FAT32/exFat - overheating the system (because cooling down helped loading at least a chunk of 1TB data flawlessly. (but it was not proven for me, because I couldn't properly assess the other sources of error So the journal from that day for dm-7 device shows some hints:

# journalctl -k | grep -Ei "excryptfs|error"
Oct 17 19:15:16 HP-ENVY-Laptop-13-aq1176ng kernel: pcieport 0000:00:1c.4: DPC: error containment capabilities: Int Msg #0, RPExt+ PoisonedTLP+ SwTrigger+ RP PIO Log 4, DL_ActiveErr+
Oct 17 19:15:16 HP-ENVY-Laptop-13-aq1176ng kernel: pcieport 0000:00:1d.4: DPC: error containment capabilities: Int Msg #0, RPExt+ PoisonedTLP+ SwTrigger+ RP PIO Log 4, DL_ActiveErr+
Oct 17 19:15:16 HP-ENVY-Laptop-13-aq1176ng kernel: RAS: Correctable Errors collector initialized.
Feb 20 00:05:30 HP-ENVY-Laptop-13-aq1176ng kernel: hp_wmi: query 0x4c returned error 0x6
Feb 20 00:05:36 HP-ENVY-Laptop-13-aq1176ng kernel: ACPI BIOS Error (bug): Could not resolve symbol [\_TZ.ETMD], AE_NOT_FOUND (20230628/psargs-332)
Feb 20 00:05:36 HP-ENVY-Laptop-13-aq1176ng kernel: ACPI Error: Aborting method \_SB.IETM._OSC due to previous error (AE_NOT_FOUND) (20230628/psparse-529)
Feb 20 09:41:07 HP-ENVY-Laptop-13-aq1176ng kernel: Buffer I/O error on dev dm-7, logical block 0, async page read
Feb 20 09:41:07 HP-ENVY-Laptop-13-aq1176ng kernel: Buffer I/O error on dev dm-7, logical block 0, async page read
Feb 20 09:41:07 HP-ENVY-Laptop-13-aq1176ng kernel: Buffer I/O error on dev dm-7, logical block 0, async page read

[.. many more ..]

Feb 20 09:41:52 HP-ENVY-Laptop-13-aq1176ng kernel: buffer_io_error: 6 callbacks suppressed

[.. many more ..]

Feb 20 09:42:01 HP-ENVY-Laptop-13-aq1176ng kernel: Buffer I/O error on dev dm-7, logical block 8192, async page read
Feb 20 09:42:01 HP-ENVY-Laptop-13-aq1176ng kernel: Buffer I/O error on dev dm-7, logical block 8192, async page read
Feb 20 09:42:01 HP-ENVY-Laptop-13-aq1176ng kernel: Buffer I/O error on dev dm-7, logical block 16384, async page read
Feb 20 09:42:01 HP-ENVY-Laptop-13-aq1176ng kernel: Buffer I/O error on dev dm-7, logical block 16384, async page read
Feb 20 09:42:01 HP-ENVY-Laptop-13-aq1176ng kernel: Buffer I/O error on 

[.. many more ..]

Feb 23 14:43:21 HP-ENVY-Laptop-13-aq1176ng kernel:  filemap_fdatawait_range_keep_errors+0x12/0x50
Feb 23 16:19:36 HP-ENVY-Laptop-13-aq1176ng kernel:  filemap_fdatawait_range_keep_errors+0x12/0x50
Feb 23 20:43:48 HP-ENVY-Laptop-13-aq1176ng kernel:  filemap_fdatawait_range_keep_errors+0x12/0x50
Feb 25 04:04:24 HP-ENVY-Laptop-13-aq1176ng kernel: ecryptfs_decrypt_page: Error attempting to read lower page; rc = [-4]
Feb 25 04:04:24 HP-ENVY-Laptop-13-aq1176ng kernel: ecryptfs_read_folio: Error decrypting page; rc = [-4]
ecryptfs_read_folio: Error decrypting page; rc = [-4]

[.. man more ..]