Lil Tay is making headlines for allegedly rolling in dough after being on OnlyFans for only two weeks … but another star who’s raked in millions on the adult site is calling BS.

Here’s the deal … Lil Tay claims she’s made $15 million since she debuted on OF … and she used the Benjamins to take a shot at dethroning Sophie Rain, who also made bank on the site pretty damn fast.

Sophie tells TMZ … she finds it very hard to believe Lil Tay has made the millions she claims in such a short amount of time … ’cause that kind of cash takes months to pile up — and you need a damn good team to help market you!

SR figured after she became a star, there would be haters coming at her — witness Lil Tay and Annie Knight — but Sophie tells us she couldn’t care less. It doesn’t get to her … and she only addresses the trash talk when asked.

TMZ’s recent documentary “The War Over OnlyFans” explored both sides of the 18+ porn site — the glam platform making some people millionaires … versus the toxic platform destroying lives.

Sophie tells us … she’s managed to navigate all the pitfalls of what makes the site dangerous for some by sticking to her boundaries … no matter how much money she’s offered to go a little further. And that means she’s still a firm NO on nudity and sex acts.