How do I roll back versions?

Please note, if you do this you will lose all your save data for every game on your Switch, profiles, screenshots, videos, etc. You can use your switch online subscription to keep some save data in the cloud, but not every game allows you to do this. The instructions are basically the same as for Super Mario Odyssey, outlined here: https://www.speedrun.com/smo/guide/qbeq4 .

So, first, backup the saves you want to keep to the cloud - go System Settings > Data Management > Save Data Cloud Backup. (Again, note that this doesn't work for every game, so there's a chance you lose your save data).

Now, factory reset your Switch. (https://www.nintendo.co.uk/Support/Nintendo-Switch/How-to-Delete-All-Content-and-Settings-on-the-Nintendo-Switch-1379045.html) Go System Settings > System > Formatting Options > Restore Factory Settings > Next > Restore Factory Settings.

Without connecting to the internet, (i.e. do not put your router's wifi code into the Switch) disable auto updates - go System > System Settings and turn Auto-Update Software to Off.

You should now be able to use the physical cart to play whatever version is on the cart.