msdosfs: Lookup of some existing files fails when mounting with long names

I recently got an USB stick which contains a bunch of mp4 files
that I want to watch on an ElectroBSD amd64 system currently based
on stable/15 b718f7d881.

Unfortunately some of the files can't be looked up when
mounting the file system with long file names (the default).

The stick could be copied to a file without problems and the
issue remains reproducible.

When the image is mounted with:

   fk@t520 ~ $sudo mount_msdosfs -m 640 -M 750 -L de_DE.UTF-8 -u youtube -o ro -l /dev/md0p1 /mnt/datentausch/

some files can't be properly looked up:

   [youtube@t520 ~]$ ls -lh /mnt/datentausch/*pstei*
   ls: /mnt/datentausch/Epstein-Akten Deutsche Namen aufgetaucht ?í´.mp4: No such file or directory
   -rw-r-----  1 youtube fk  413M 2026-04-13 20:47:46 /mnt/datentausch/Epstein Es ist noch widerlicher, als wir glauben.mp4
   -rw-r-----  1 youtube fk  1.2G 2026-03-07 00:57:00 /mnt/datentausch/Epstein, Ukraine, Covid - Uns müsste schlecht werden.mp4

When mounting the image with:

   fk@t520 ~ $sudo mount_msdosfs -m 640 -M 750 -L de_DE.UTF-8 -u youtube -o ro -s /dev/md0p1 /mnt/datentausch/

the offending file appears and can be opened by vlc so I have a work-around:

   [youtube@t520 ~]$ ls -lh /mnt/datentausch/*pstei*
   -rw-r-----  1 youtube fk  1.2G 2026-03-07 00:57:00 /mnt/datentausch/epstei~1.mp4
   -rw-r-----  1 youtube fk  349M 2026-03-21 09:50:54 /mnt/datentausch/epstei~2.mp4
   -rw-r-----  1 youtube fk  413M 2026-04-13 20:47:46 /mnt/datentausch/epstei~3.mp4

There are a couple of other files that are affected but their
file names are sensitive ...

When ls complaints about them, their names contain suspicious
strings like "?í´¥", "?í·", "?í´¥", "?íº" etc.

Mounting the file system without the -L option results in even
more lookup failures.

Reverting 29af6d2e2ec9fe8 didn't make a difference.

AFAIK, the files were copied to the stick from a GNU/Linux system.

Fabian