lol, that's still a thing? I was hitting the same problems 3 years ago and that already put me off btrfs forever. It's fine I guess nobody needs their FS to be writable anyway.https://twitter.com/septajohn/status/1265192454480777217 …
See for example https://btrfs.wiki.kernel.org/index.php/FAQ#Help.21_Btrfs_claims_I.27m_out_of_space.2C_but_it_looks_like_I_should_have_lots_left.21 … or https://btrfs.wiki.kernel.org/index.php/FAQ#or_My_filesystem_is_full.2C_and_I.27ve_put_almost_nothing_into_it.21 … "So, in general, it is impossible to give an accurate estimate of the amount of free space on any btrfs filesystem. Yes, this sucks." I agree.