This was voluntarily before 2022 and has been removed entirely since 2022:

https://www.bundestag.de/dokumente/textarchiv/2022/kw39-de-p...

https://www.vaticannews.va/de/kirche/news/2022-10/deutschlan...

I'm a little confused. It's still a field on the registration form and is used to collect Church tax, right? My last Anmeldung was in 2019 so I might have missed something.