I believe this is a bug in Firefox for iPadOS: when a bluetooth mouse or trackpad is connected to the device, if I’m in Firefox and I tap (with my finger) in the address bar to type in a URL or search term, it doesn’t let me change the focus to it. It briefly starts to bring up a keyboard, then that disappears and I’m not given the opportunity to type anything. If I click (with the bluetooth mouse or trackpad) in the address bar, it does then allow me to type.

In almost all other apps, tapping or clicking does the same thing, regardless of whether a mouse is connected at the time.