On 9.09.21 г. 3:47, Sam Edwards wrote:

My primary hypothesis is that there's some write bug in Linux 5.14.1.
I installed some package updates right before btrfs detected the
problem, and most of the files in the `btrfs check` output look like
they were created as part of those updates.

SO what was the last workload that got run on this server. The
btrfs-progs log suggests the last 2 transactions have been lost
expecting 66655 vs finding 66653. Also looking at the missing file names
it suggests you were fiddling with some windows development software? I
can see a mix of .dll.so files and also a bunch of just .dll files. SO
what was the last thing you installed on that machine? Are you using
dual boot by any chance on the same disk?