I have the problem in combination with both

I have uninstalled Snap Firefox and installed PPA Firefox

Suddenly it updates, and when I restart, the PPA Firefox is gone! It is back to the Snap Firefox

Also the Snap Firefox does not start, because I use a user that is not in the snap group. So after each update, I have to uninstall it and reinstall the PPA one

How do I disable the snap updates permanently?