A lot of times you will see the format string for the fedora version in the .repo file. This means its probably looking for f41. Since fedora updates fast, third party repos are usually slow to move to the next version and this repo probably doesnt exist causing dnf to fail. You can try and change the format string to the last available version. It usually works without issue, and updates aren’t disabled as long as the vendor updates that version

So this isn’t really an answer on how to migrate but this solution has worked well for me.

I define the toolboxes config with it, and if it gets destroyed, recreating it is as simple as creating a new one with the same name. You could upgrade or downgrade by just creating a new toolbox with the version you want.