Tiling over painted surface?

[Happymunchkin567]

I want to tile a mini splash back in our toilet. The sink is tiny, so I was hoping it'd just be a really quick little upgrade with one of those sheets of mosaic tiles.
The Internet tells me you can't tile onto a painted surface, but I'm thinking I'll just ignore it - am I being really stupid? Has anyone tried this and succeeded? (Or lived to regret it 😅)

Thanks!

If you use something like a screwdriver to scratch deep lines into the paint before you tile then it will be fine. If not then the tiles stick to the paint rather than the wall and the weight just pulls the tiles off. Definitely did not do this myself.

Strip out the paint or just sand it down with a coarse sandpaper.

Sand it first