Comment # 7 on bug 1205813 from Felix Niederwanger

Hard to know. btrfs can only detect those issues via checksuming but is itself
not able to tell you where they come from - they can originate from basically
anywhere. Faulty hardware or bad connectors are by far more likely than a
filesystem issue itself.

IMHO - don't bother trying to repair such issues. If you could save the data
elsewhere then nuke the filesystem and start over. I would be suspicious on the
hardware itself and wouldn't rely on it for a couple of months after such a
failure, i.e. always keep backups and assume it's going to shoot itself in the
foot again. At this point I would say it's safe to assume the disk is somehow
flanky until proven otherwise.

But those are just my two cents - Your hardware, your rules :-)