How can I mount or repair this ExFat USB stick using my Macbook?

I have a 64 GB USB-C flash stick from Samsung that was new in October 2024, which I formatted with a tool from my car's manufacturer that it insisted on. Making it a ExFAT volume that contains map updates and optionally media like MP3s. I had success reading it in the car, and success adding media to it using the Mac when I was on MacOS 14 Sonoma. Now I insert it on my updated MacBook running MacOS 15 Sequoia, and it just doesn't mount. It shows up in Disk Utility and as disk4 with disk4s1. Isn't ExFAT supported and shouldn't it work? I'll show you what I tried so far, and I wonder if there's something else I should try. Here's what the terminal says about mounting it read only:

dlamblin ~ % diskutil mount disk4s1
Volume on disk4s1 failed to mount
If you think the volume is supported but damaged, try the "readOnly" option
dlamblin ~ % diskutil mount readOnly disk4s1
Volume on disk4s1 failed to mount
If you think the volume is supported but damaged, try the "readOnly" option

Prepending sudo doesn't change the output to either of these. And perhaps you want to see what it says in Disk Utility: Oh, and First Aid complains about permissions, but the terminal version of diskutil doesn't behave any better with sudo permissions. E.G. with sudo:

dlamblin ~ % sudo diskutil mountDisk readOnly disk4
Volume(s) mounted successfully
dlamblin ~ % df -h
Filesystem        Size    Used   Avail Capacity iused ifree %iused  Mounted on
/dev/disk3s1s1   460Gi    10Gi   324Gi     4%    412k  3.4G    0%   /
devfs            208Ki   208Ki     0Bi   100%     720     0  100%   /dev
/dev/disk3s6     460Gi    15Gi   324Gi     5%      15  3.4G    0%   /System/Volumes/VM
/dev/disk3s2     460Gi   6.4Gi   324Gi     2%    1.2k  3.4G    0%   /System/Volumes/Preboot
/dev/disk3s4     460Gi   2.2Mi   324Gi     1%      51  3.4G    0%   /System/Volumes/Update
/dev/disk2s2     500Mi   6.0Mi   481Mi     2%       1  4.9M    0%   /System/Volumes/xarts
/dev/disk2s1     500Mi   5.4Mi   481Mi     2%      33  4.9M    0%   /System/Volumes/iSCPreboot
/dev/disk2s3     500Mi   2.7Mi   481Mi     1%      85  4.9M    0%   /System/Volumes/Hardware
/dev/disk3s5     460Gi   102Gi   324Gi    24%    1.0M  3.4G    0%   /System/Volumes/Data
map auto_home      0Bi     0Bi     0Bi   100%       0     0     -   /System/Volumes/Data/home
/dev/disk3s7     460Gi   2.0Gi   324Gi     1%    139k  3.4G    0%   /nix
/dev/disk3s3     460Gi   986Mi   324Gi     1%      38  3.4G    0%   /Volumes/Recovery
dlamblin ~ % sudo diskutil verifyDisk disk4s1
A whole disk must be specified
dlamblin ~ % sudo diskutil repairDisk disk4s1
A whole disk must be specified
dlamblin ~ % sudo diskutil verifyDisk disk4
Unable to verify this whole disk: A GUID Partition Table (GPT) partitioning scheme is required (-69773)
dlamblin@ ~ % sudo diskutil repairDisk disk4
Unable to repair this whole disk: A GUID Partition Table (GPT) partitioning scheme is required (-69773)

Maybe it's MBR partitioned now? But again, it worked before. Was there some MBR support I forgot I added to Sonoma that I should add or enable? **Updates per comment requests**: Again, kindly note that I can read the contents of this USB stick in my car, and on a Windows machine. I can modify them if I like. I cannot mount it at all on my MacBook Pro 16 Nov 2023 with Sequoia 15.3.1.

➜  ~ sudo fsck_exfat -q /dev/disk4s1
QUICKCHECK ONLY; FILESYSTEM CLEAN
➜  ~ sudo fsck_exfat -d -n /dev/disk4s1
** Checking volume.
** Checking main boot region.
125313091 total sectors; 512 bytes per sector
FAT starts at sector 2048; size 3840 sectors
489480 clusters starting at sector 6144; 131072 bytes per cluster
Root directory starts at cluster 4
Read      offset = 0x000000100000  length = 0x001000
** Checking system files.
Read      offset = 0x000000340000  length = 0x020000
Found active bitmap; first cluster 2, length 61185
** Checking upper case translation table.
Read      offset = 0x000000320000  length = 0x020000
Found upcase table; starting cluster 3, length 5836
** Checking file system hierarchy.
Directory /
Directory /System Volume Information
File      /.lge.upgrade.xml.enc
Directory /HU
Directory /whatsnew
File      /2023_GV60_USA.ver
File      /$TXRAJNL.DAT
Read      offset = 0x000000360000  length = 0x020000
File      /System Volume Information/WPSettings.dat
File      /System Volume Information/IndexerVolumeGuid
Read      offset = 0x0000003c0000  length = 0x020000
Directory /HU/images
Directory /HU/firmware
Read      offset = 0x000242c80000  length = 0x020000
File      /whatsnew/whatsnew.tar.gz.enc
Read      offset = 0x0000003e0000  length = 0x020000
File      /HU/images/coconut-rootfs.tar.gz.enc
File      /HU/images/coconut-vr_NAM.tar.gz.enc
File      /HU/images/A_gos2-fs_20_qnx.img.enc
File      /HU/images/kernel-update-CLU.tar.gz.enc
File      /HU/images/kernel-update.tar.gz.enc
File      /HU/images/kernel-updater.enc
File      /HU/images/navi_NAM.md5_.enc
File      /HU/images/navi_NAM.tar.gz
File      /HU/images/nav_NAM_JW.sign
Read      offset = 0x000000400000  length = 0x020000
File      /HU/firmware/update.tar.gz.enc
** Checking active bitmap.
Checking bitmap cluster 2
Read      offset = 0x000000300000  length = 0x020000
0 clusters were marked used, but not referenced
0 clusters were marked used and CLUST_BAD
0 clusters were marked free, but referenced
** Rechecking main boot region.
** Rechecking alternate boot region.
** The volume  appears to be OK.
➜  ~ sudo fsck_exfat -y /dev/disk4s1
fsck_exfat: Opened /dev/rdisk4s1 read-only
** Checking volume.
** Checking main boot region.
** Checking system files.
** Checking upper case translation table.
** Checking file system hierarchy.
** Checking active bitmap.
** Rechecking main boot region.
** Rechecking alternate boot region.
** The volume  appears to be OK.
➜  ~ sudo diskutil mount disk4s1
Volume on disk4s1 failed to mount
If you think the volume is supported but damaged, try the "readOnly" option
➜  ~

~ sudo fdisk /dev/disk4
Disk: /dev/disk4	geometry: 7800/255/63 [125313283 sectors]
Signature: 0xAA55
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 1: 07    0   3   4 - 1023 254  63 [       192 -  125313091] HPFS/QNX/AUX
 2: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
 3: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
 4: 00    0   0   0 -    0   0   0 [         0 -          0] unused

I also tried a different mount command; confused that I got a permissions bases error.

➜  ~ sudo mkdir -p /Volumes/samsung; sudo mount_exfat /dev/disk4s1 /Volumes/samsung
mount_exfat: /dev/disk4s1 on /Volumes/samsung: Operation not permitted
➜  ~ sudo rmdir /Volumes/samsung