The biggest one is the Firefox ESR build from the pmOS repos with the custom userChrome.css that tries to fit everything onto the Pinephone's screen. I pretty consistently encountered pop-up prompts (for example, in the built-in password manager) that ran off the edge of the screen in both portrait and landscape. Zooming out sometimes helped, but then the text was unreadable and the buttons too small to press. There was also no forward button in either the overflow menu or the nav bar. The Phosh settings app had similar problems.
