I know this issue has been raised before.... On some of my fingers, despite cutting my fingernails very short, in some hand movements my nails get stuck between white keys and black keys (the tiny space bewteen these).......I even got surgery on one if my fingers, to remove 5 mm of nail and replace the flesh underneath with skin...... Once the nail get stuck, this is real!
Intuitively, I would either play some notes landing in between 2 black keys, or slide my finger frome the tip of the key towards the piano, maintaining the key depressed to have best legatissimo. These situations where when my fingernails would slide into the gap between the white key and the black one.