First of all, you should know that by default if you want to revert your WINDOWS 11 upgrade to Windows 10, you only have 10 days.
To be fair you can extend this period up to 60 days if you run a shell command before the original ten days is up.
DISM /Online /Set-OSUninstallWindow /Value:60
You can use any value, between 10 and 60 but not more than 60.
So in other words, you have to know you're probably going to want to revert your install before the ten days are up in order to decide to give yourself 60 days to evaluate Windows 11. But if you haven't planned ahead to revert back and discover on Day 12 that you'd like to go back, the command won't work.