Well even going back with Timeshift I had problems because the update touched some user configurations, but I read there was some fixes released so I updated again, then went back again to 5.27 and thankfully, everything worked.
On the other hand, I just tried removing the Index of /user repo and it seems it worked, now I just have 10 updates related to other things.
In the state Plasma 6 seems to be, more than a few days, I think I’ll wait a few monts…
EDIT: I’m not using BTRFS with Timeshift but RSYNC