F-Droid Build Status was updated to 5.6.4 and no one will get this update. Why? Well, the app is now built reproducibly so if you have it installed you need to uninstall it and then reinstall it. (Yes, we wish this switch to be easier to perform, but the UI is not there yet)
Has there been any previous apps we need to install and uninstall?
I think the fdroid app will let you know if you need to do so when you try to update the app manually