thanks for the clarification.
it's to much risk to remove all, and then to "try" smart setup, if we don't know the reason of failure, there is another ticket about failed 12.3 setup:
Installation failed for Delphi 12.3 - VCL / TMS VCL UI Pack - TMS Support Center.
I need to have working dev. environment 7/24. can't risk again. as for now Delphi 12.3 works, with old version of TMS components. I'll think what to do next...