When switching between Python versions in CloudLinux's Python selector, you may find that the version 3.8 will only return 503 errors.
The issue is mostly caused by the lack of the Python 3.8 WSGI package. On out of date versions of LiteSpeed, the package needs to be installed manually.
To work around this, first ensure that LiteSpeed is up to date. LiteSpeed must be at version 5.4.10 for this to work. Once that is confirmed, execute the following script from LiteSpeed. It will pull the required Python Selector packages: