So I think Dirk Graefe's suggestion is good, that the notary confirms that the process has been submitted to the tax office and maybe it's possible to get a confirmation from the tax office as well. But whether both do that is questionable, as is whether it will be sufficient for the bank.
The suggestion with the ranking certificate from the notary is what we would like, namely a notary confirmation, but that only exists after the real estate transfer tax payment. At least that's what google spits out for me. I am not a lawyer and find all these terms awful.
I need to find out more precisely about the [Auflassungsvormerkung], I'm not exactly sure if we have it and/or if something is still missing there. But thanks for the hint, I will check directly with the bank whether that is sufficient.
Thanks to everyone.
Best regards, Sophia