Unlike previous bans, this one seems to be tied to phone numbers. So even users with non iOS/Google Play versions of the app can't access the blocked groups as long as they have a german number. There is a more in-detail article about the nitty-gritty on how the blocking seems to work:
estranhosidade|4 years ago
https://reclaimthenet.org/germany-demands-telegram-censorshi...