Makeup at 10 years old?

Best keep quiet unless you want to be labelled as a boring old fart. Young girls do not do their youthful complexions any favours by slapping on skincare products. But would they listen? NO!

Best not to comment as OPs have said. Not a fan of such young children wearing make up or using facial creams etc. Some creams and lotions have ingredients that are harmful
for young skin.
My friend gets a rash in winter. Cold exposure Urticaria.

I don't like young girls wearing make-up or nail varnish, false nails etc. but I gather there is intense interest in beauty products designed for young skins, for cleansing , toning , nourishing etc, developing sensible habits for life. Better than hanging round the Rimmel counter buying 'Pink Ice' lipstick and teal blue eye shadow, my first make-up faux-pas.

The girls start with skincare very young these days ...around 8 or 9 ....there's a sephora in every big town now....I was in the liverpool one last week....was full of young primary aged girls

I have a GD, same age , just turned 10, who wears make-up . When I told my son she was too young, he said it’s up to my wife - that put me in my place 😂

Say nothing ... my DGD is the same and is now 12. She now uses her makeup in a very subtle way and she looks beautiful. I was a bit concerned initially but she seems to have experimented and found what suits her without getting carried away. I suspect that if it had been denied her she might have eventually rebelled and gone over the top.
My other DGD is transitioning and on testosterone which is more worrying.

I think it's a bit too young. At that age girls still have a lovely youthful bloom.

My GD started to wear make-up at 13. Still too young in my opinion. We tried to remind her that make-up is intended to enhance your good features and not to paint over everything, so to use it carefully. She's a bit heavy on the mascara (so was I at 15) but otherwise doesn't go over the top.

I would continue to say nothing. I am not personally a fan of young children using makeup, but neither do I think that others should interfere with how parents raise their children unless they are in clear and present danger. It's not worth it, as doing so is likely to cause issues, particularly between in-laws.

Just be there for her, and when she's with you you can encourage activities which are more suitable for a 10 year old. She might grow out of it anyway.