samba - Jun 2022 - Raising Domain and Forrest level in mixed environment (Samba & Win 2k19)

I?m trying to raise the domain and forrest functional level to 2012R2 because of
Exchange. However, raising the level on the main Windows DC fails because it
complains about the Samba DCs NOT ?running the appropriate version of windows?.

I then tried to from a Samba DC. I transfered the FSMO role schema to the Samba
DC and ran "samba-tool domain schemaupgrade? which reported successfully as
88 (in the Wiki it still mentions 69 to be max). I checked on other DCs
including the Windows one and it propagated.

Afterwards I tried to run:
samba-tool domain level raise --domain-level=2012_R2
ERROR: Domain function level can't be higher than the lowest function level
of a DC!

The Windows server runs 2k19, the Samba DCs all run Louis? Samba version
4.15.7-Debian.

How can I achieve my goal?

Greetings, Alexander