During normal use I wouldn’t notice until I started reading webtoons and manga on my phone which shows a lot of white color that you don’t typically see. And that’s when I’d see the burn in my screen had picked up.

As for why there is more fuss about monitors than phones is because people use monitors for many more years than phones. And can use them for many more hours with lot of static elements with sometimes one program being used day in and day out. Its same reason why there is less talk of burn in for TVs versus monitors where TVs are more likely to have constantly changing visuals than monitor use case.