On Friday, August 23, 2019 at 3:40:18 PM UTC-4, A K wrote:
I would like to repair this damage.

It is in my shower.

It looks like some kind of paint/coating was sprayed over the tile.

What can I use to repair it?

https://imgur.com/a/1MqPx3z

Weird, any idea how it got there? Are you sure it's something on
top of the tile? If you think it's paint, then paint remover?
Tile would be impervious to that. If you have already something else,
eg paint thinner, acetone, nail polish remover, gasoline, you could try
that first.