This is a duplicate of calendars keep being turned on in calendar app (visibility) since update to 1.0x and it’s fixed with 1.0.4. Please follow up there if there are further problems.
F-droid version not available again
Maybe because the code is moving to GitLab?
https://f-droid.org/wiki/page/at.bitfire.davdroid/lastbuild_81 (from https://f-droid.org/wiki/page/at.bitfire.davdroid#0.9.0.3) doesn’t sound like a GitLab problem.
Sorry. I didn’t search the forum… Got it, thanks!