I noticed that on Firefox 91.12, Bricks 1.8.3, the default dropdown icon on the Nav (Nestable) element displays huge - 1700px x 1700px, instead of the standard 1em x 1em. I was able to reproduce this error on a fresh install of Bricks.
I did not try to reproduce it yet. Is it the same in the frontend of the site? And more important: Is there a reason you are using a two year old version of Firefox? As far as I can see the current ESR release version is 102.13.0.
That’s a good point about the version of Firefox! This is not my usual device, I was using a public computer. It’s the same on the frontend of the site, yes. The link I included looks as I described on that version of Firefox.