Typically when there are “can’t mount” issues with btrfs it’s cause the write log got corrupted, and memory errors are usually the cause.
BTRFS needs a clean write log to guarantee the state of the blocks to put the filesystem overlay on top of, so if it’s corrupted btrfs usually chooses to not mount until you do some manual remediations.
If the data verification stuff seems more of a pain in the ass than it’s worth you can turn most of those features off with mount options.
I run btrfs on every hard drive that my Linux boxes use and there’s the occasional hiccup but I’ve never run into anything “unrecoverable.”
I will say that compared to extfs, where the files will just eat shit if there’s a write corruption, because btrfs tries to baby the data I think there appear to be more “filesystem” issues.