[zejn]

Synology does not use vanilla btrfs, they use a modified btrfs that runs over mdraid mirror, which somehow communicates with btrfs layer to supposedly fix errors, when they occur. It's not clear how far behind that fork is.

[ksec]

Synology are still shipping kernel 5.10 on their latest model. And 4.4 only a few years prior.

I am hoping we will get ZFS from Ubnt NAS via update.