I always run my app in Safari. Because. I’ve never seen this. I’m not sure how to help, but if I were you I would step through the Bubble debugger – maybe there’s something extra firing when you click that button? I would also take a look at the dev utils of Safari to see if you can spot something changing.
If I were to bet, that looks like a 60px height, the default of a new group. My other hypothesis, the (now old) Material icons has a bunch of funky math that did all sorts of weird stuff.