I’m using it currently on a Pixel 7 Pro on GrapheneOS on Android 15 with no issues if that helps

Perhaps right click on the sidebar -> disable compact mode? I haven’t had any issues moving tabs between windows, but then again I keep the sidebar persistent

Perhaps Ladybird once it’s released?

If you’re looking for a reasonable FOSS swipe keyboard, try AnySoftKeyboard. While still a step below the non FOSS keyboards I’ve used before like Swiftkey, it gets the job done reasonably well