[2022] Game crashes after clicking "New game"

Is this only since 1.5.1 ? What happens if you revert to an older version, as a test?  

Did your clean reinstall include making sure there are no files or folders left under either the Steam CK3 or Documents CK3 locations, before installing again?

Note that when you revert to patches before 1.5 you must disable the Royal Court DLC as well - it causes crashes to earlier versions.