Different timestamps in SFTP "ls -l" vs. "ls -lh"

I have a 3rd-party SFTP server on which I want to check some file timestamps. However, I do get different results for the same file if I use ls -l vs. ls -lh:

sftp> ls -l
[...]
-rwxrwxrwx 1 0        0               1963 Nov 15 08:49 foo.txt
[...]

sftp> ls -lh
[...]
-rwxrwxrwx    0 0        0            1.9K Nov 15 07:49 foo.txt
[...]

sftp> ls -l foo.txt
-rwxrwxrwx    0 0        0            1963 Nov 15 07:49 foo.txt

sftp> ls -lh foo.txt
-rwxrwxrwx    0 0        0            1.9K Nov 15 07:49 foo.txt

As you can see, the timestamp in ls -l is 08:49 whereas the other commands have 07:49. The server is in Germany which currently is 1h later than UTC, so my guess is that 07:49 is UTC whereas 08:49 is Berlin time. However, my machine is on UTC:

$ cat /etc/timezone 
Etc/UTC

My understanding is that, according to the SFTP standard, all timestamps should be in UTC. However I'm not sure whether that understanding is correct (given that there are so many different versions of the standard). I also don't know whether the sftp tool somehow postprocesses the timestamps (man sftp doesn't mention timezones or timestamps at all). What could be the reason for the difference?