don't worry, unity generates some extra files to make it compatible for all pcs, It's clean
Unity Editor version 6 changed the minimum windows version to be able to run/play builds(standalone player) to Windows 10 version 21H1 (build 19043) or newer
2023.1.20f1 is the last version that would build for older windows versions aswell other lower minimum requirements for other platforms example for android
Unity 6 = > 6.0 (API 23)+ 2023.1 => 5.1 (API 22)+