Half of ratings of this app are one star, but the average is 4.4 stars

I found this iOS app Photopia - https://apps.apple.com/us/app/photopia-photo-editor/id1467875471

I opened the ratings and most of them are one star. But at the top, it shows "4.4 out of 5". Does anybody know why? How does Apple compute the rating of apps?

I noticed it, because I provide a web app www.Photopea.com , and I get about four emails a week from users of "Photopia", saying that it took $80 from their credit cards, and wanting their money back.

As it is a bit exhausting to explain to these people, that we have nothing to do with it, is there anything I could do to make Apple take down this scammy app? I do not own any Apple device.