Hi,
I can now reproduce using fio:
I looked around in MariaDB issue tracker and found https://jira.mariadb.org/browse/MDEV-26674 which lead me to https://github.com/MariaDB/server/commit/de7db5517de11a58d57d2a41d0bc6f38b6f... -- it's a conditional based on $KV and I hit that kernel regression during one of my bisect attempts (see https://lore.kernel.org/all/701f3fc0-2f0c-a32c-0d41-b489a9a59b99@whissi.de/).
Setting innodb_use_native_aio=OFF will prevent the problem.
This helped me to find https://github.com/axboe/fio/issues/1195 so I now have a working reproducer for fio.
$ cat reproducer.fio [global] direct=1 thread=1 norandommap=1 group_reporting=1 time_based=1 ioengine=io_uring
rw=randwrite bs=4096 runtime=20 numjobs=1 fixedbufs=1 hipri=1 registerfiles=1 sqthread_poll=1
[filename0] directory=/srv/machines/fio size=200M iodepth=1 cpus_allowed=20
...now call fio like "fio reproducer.fio". After one successful fio run, fsfreeze will already hang for me.