The "python3.x-intel64" executable was added for macOS "universal2" builds by Issue44009 in the 3.9.5 and 3.8.10 releases. As described in the issue and the changelog entries, the rationale is:

"Provide “python3.x-intel64” executable to allow reliably forcing macOS universal2 framework builds to run under Rosetta 2 Intel-64 emulation on Apple Silicon Macs. This can be useful for testing or when universal2 wheels are not yet available."

We provided an analogous "python3.x-32" executable for macOS "intel" (x64_64 and i386 archs) builds for a similar reason.

Although it is mentioned in the changelog (and the python.org macOS installer ReadMe), I didn't anticipate that there would be anyone attempting to build and submit a universal binary for Apple notarization and who would be affected by this change: sorry about that! You can just either add the new executable to your codesigning script or you could delete the file before codesigning if you don't have a need to provide it to your users: it isn't needed unless you want to reliably force running under Rosetta 2 Intel emulation on an Apple Silcon Mac.