Convert Windows Server 2019/2022 evaluation to full version AD DS

It's not supported to convert an evaluation after domain controller promo, but you can easily stand up a new one for replacement.

The two prerequisites to introducing the first 2019 or 2022 domain controller are that domain functional level needs to be 2008 or higher and older sysvol FRS replication needs to have been migrated to DFSR
https://techcommunity.microsoft.com/t5/Storage-at-Microsoft/Streamlined-Migration-of-FRS-to-DFSR-SYSVOL/ba-p/425405

I'd use dcdiag / repadmin tools to verify health correcting all errors found before starting any operations. Then stand up the new 2019 or 2022, patch it fully, license it, join existing domain, add active directory domain services, promote it also making it a GC (recommended), transfer FSMO roles over (optional), transfer pdc emulator role (optional), use dcdiag / repadmin tools to again verify health, when all is good you can decommission / demote old one.

--please don't forget to upvote and Accept as answer if the reply is helpful--

I couldn't find any official source stating that the DC conversion from EVAL to Retail is NOT SUPPORTED. All Microsoft is saying that, and I quote, "YOU CAN'T". https://learn.microsoft.com/en-us/windows-server/get-started/upgrade-conversion-options#:~:text=You%20can%27t%20convert%20an,to%20Windows%20Server.

Yes, that's correct, it simply is not supported.

Is there any reliable source statin this, other than hearsay? Seems like an urban legend to me.

but are you sure the latest version does not support the conversion because it ended without errors?
domain and forest functional level 2016
dcdiag and repadmin will not show any errors, except for the error below

c:\dcdiag /q
There are warning or error events within the last 24 hours after the SYSVOL has been shared.
Failing SYSVOL replication problems may cause Group Policy problems.
......................... XXXX failed test DFSREvent

Eventlog:
Package Windows ServerStandardEval Edition was successfully changed to the Absent state.
Package Windows ServerStandard Edition was successfully changed to the Installed state.
A reboot is necessary before package Windows ServerStandardEval Edition can be changed to the Absent state.
A reboot is necessary before package Windows ServerStandard Edition can be changed to the Installed state.

Are you sure you need to move the domain controller?