[  186.277795] Btrfs detected SSD devices, enabling SSD mode
[  188.477443] btrfs: unlinked 6 orphans
[  188.477451] btrfs: truncated 1 orphans
[  411.837015] btrfs: unlinked 13 orphans
[  414.373500] btrfs: unlinked 35 orphans

This seems to hint that I lost random files and that I don't know what they are.

I suppose I can go back to my latest hourly snapshot which is more likely to not have
truncated or missing files.

I believe it just means "the space for stuff that was
deleted/unlinked/truncated, but which didn't get reclaimed before the
crash".