customization – Clean startup with back up

Whenever there are bugs Wolfram Support suggests to do a clean restart by holding Ctrl + Shift during start-up (often they recommend that without even warning the user that this will delete all their settings). How do I do such a clean restart while preserving a back-up so that I can go back to my custom configuration after a test in the factory setting environment?

I am using “12.1.1 for Linux x86 (64-bit) (June 19, 2020)”.