My personal gripe with mobile Firefox is searching by using the address bar.
I have had countless times where I put in my search prompt, followed by pressing the little X all the way on the right and thus clearing the address bar. My brain just really expects an enter button to be there.
I think my current record is entering a search term and then clearing it literally directly 3 times in a row, getting more and more confused each time.
Magic Earth (while not FOSS, it’s privacy oriented though) can do this.
There’s also Transportr, but AFAIK it’s been unmaintained for quite a while now, so it may not work / stop working soon.