foris configuration was wiped because of move from foris to foris-controller package
This is bug in updater (I was personally sure that we were handling this case but seems that not) turris/updater/updater#305 (closed).
This slipped trough testing so it landed in HBS with version of %Turris OS 5.1 . We should release hotfix (to revert old version from snapshots if file is empty) in %Turris OS 5.1.1. Fix in updater should continue.