Regular nail polish is fine since you want it there,but if it cracks and you would take it off then it could be a problem. If one has a loose nail that is a chatitzah also it should be removed
What happens if you discover a loose nail on shabbos?
It’s a chatzisa for the rest of shabbos until you can peel the rest of them off or just fix that one up, no?? I think you have ta put a plasic bag over the hand that has the chatziza, I remember this faguely when one of my friends had a plaster last year on the hand and had to do this in order to wash.
The way I was told to remove nailpolish on shabbat (that is a chatziza) is that you could rub nailpolish remover on your nail with out a cotton ball or napkin.