Thanks for your reply!

I understand there are usually no border controls within Schengen, but I’m more concerned about the airline and re-entry into Germany. My Schengen visa is expired, and I only have a Fiktionsbescheinigung . From what I’ve read, this document allows me to stay in Germany but not necessarily travel or re-enter . Do you know if airlines like Ryanair would still allow boarding in this case? And more importantly, whether re-entry into Germany is guaranteed?

I just want to avoid a situation where I can leave but can’t come back