From my non-lawyer understanding it's not that. It's about sex trafficking more generally.

Here's the most notable case I'm aware of: https://en.wikipedia.org/wiki/GirlsDoPorn

Then there was the recent drama with civitai https://civitai.com/articles/14945/credit-card-payments-paus...

I believe some of these sex trafficking laws implicated a broad sweep in their litigation and Visa/Mastercard doesn't want to have to go to court over a these things.