Did you ever look in your app.yml to see what branch you are on? That’s the only way to tell.
There is little chance that you changed it to “main”. Unless you took explicit steps to change anything, then you are on tests-passed.
It is not dangerous to upgrade. If you think that it is, or your world would come to an end if anything happened to your site, then you should have a staging site where you can test upgrades.
But as a rule, if anything is ever wrong with your site, the answer is “rebuild”.