Meghan Markle borrowed Kate Middleton's lip gloss during the Royal Foundation Forum in 2018, which led to a controversy.

Kate was taken aback by the request, but reluctantly gave in and lent her lip gloss to Meghan.

Harry recalled this moment in his book "Spare", where Kate grimaced at the request.

The lip gloss in question is the Clarins Natural Lip Perfector, which costs $28.

The lip plumper contains shea butter, vitamin F, and has a vanilla scent.

The incident may have been a sign of things to come between the couples and their feud.

Frosty family relations are no fun.

The lip gloss controversy was just a small part of the larger issue.

The public is curious about Princess Kate's favorite lip products.