Because:
2016 CU1 is so old, ( 5 years!) that it probably cant detect the requirement
You need to get to that CU19 plus the security patch.
Update it manually - immediately
Run each step separately:
Setup.exe /IAcceptExchangeServerLicenseTerms /PrepareSchema
Setup.exe /IAcceptExchangeServerLicenseTerms /PrepareAD
Setup.exe /IAcceptExchangeServerLicenseTerms /PrepareAllDomains
Then install .net 4.8
https://learn.microsoft.com/en-us/exchange/plan-and-deploy/supportability-matrix?view=exchserver-2019#microsoft-net-framework
Then install CU19:
CU19:
https://www.microsoft.com/en-us/download/details.aspx?id=102532
Then install the security patch:
Critical Patch:
https://www.microsoft.com/en-us/download/details.aspx?id=102772
As for the other server, this is not supported:
The 2019 server has Exchange 2016 CU11
Exchange 2016 is not supported on Windows 2019. You will need to rebuild that server with a supported O/S