You, like the F-Droid repo, have downloaded from GitHub the Android Pre-release which upgrades the sync target and so requires matching pre-release versions of the desktop clients.
It seems however that the Android releases page does not have a warning like the Desktop releases page does.
Important: This pre-release will ask you to upgrade your sync target and, once it is done, only the latest clients will be able to sync with this sync target. Currently that includes the desktop app (v1.0.234+) and Android app (v1.0.337+). It means if you are using these two clients you'll be fine. However if you are using the iOS or CLI clients you might want to wait till these clients are updated. Any issue with the sync target upgrade, please post on the forum.