It’s quite likely a belief that sunscreen lotion is a bad thing that harms people.

I mean, it halfway is:

• "Sunscreen" -- stuff with a decently high SPF rating -- is a good thing that prevents cancer.

• "Suntan lotion" -- usually glorified coconut oil with fuck-all SPF rating -- is a bad thing that harms people.

• "Sunscreen lotion" -- a confused amalgamation of the previous terms -- is not a thing and only misleads people by conflating good things with harmful ones.