Comment # 1 on bug 1162471 from Jiri Slaby

(In reply to Dominique Leuenberger from comment #0)
> for Snapshot 0131, the kernel was updated to version 5.5.0. The test fails
> with 'no space left' on the disk. Considering that this test runs on VM with
> HDD configured for 40GB, this is unlikely to happen.
> 
> I reproduced this locally in a VM (based on the not-published snapshot).
> After the machine was up for a while and I keep on installing programs
> (while monitoring the disk usage) I saw an immediate jump at one point from
> 31GB free storage to 0 bytes free. After running btrfs balance, the 31GB
> where quite immediately reclaimed.

Guys, any ideas what could break btrfs this way in 5.5?