They are probably using timeshift or some advanced feature in btrfs to auto-generate snapshots so they can go back to a working state using one of them.
The way you do it is probably getting old. I say this because I do the same, but to use several distros with a shared home partition, provided I have the same GID and UID for the users. This is not recommended but only once I’ve had a problem and it was easy to solve, so I kept doing it. Installed Fedora recently with defaults in one partition and they use one fat partition (EFI), and one btrfs partition with a logical volume and some unfamiliar partitioning. I think we are maybe missing some new technologies.