I've had multiple bugs while trying to create a user from Android phone. Similar to @Sabrina's post, but perhaps worse...
I managed to sign up my email and verify it. In the "create user" page, the "Create" button was hidden by the notification with the green V at the bottom (something like "Welcome back"). I could scroll a bit to a specific spot where the text was visible. I could tap the button, but then it was only replaced by another one, this time I didn't manage to see what was written. The main bug here is that the "Welcome back" message should have disappeare I believe after a few seconds or upon scrolling.
The worse thing then was that if I tried to go back, or open another tab of campground.bonfire.cafe, I got the non-logged in front page, and tapping Login or Sign up just reopened the same page! So I was basically stuck in a loop.
I created the user from desktop, but to stop the loop I had to clear the cookies, after which I did manage to login on the mobile.
Specs: Fairphone 4, android 15, Firefox 153.0.2