Remember, the 14-0 female heavyweight started calling out the Problem Child back in 2020 ... when she challenged him for disrespecting the sport during our interview that year.

Her many callouts since have gone unanswered ... but if you thought the silence would discourage CS from going after the former YouTuber -- think again.

"The offer is always up there if Jake Paul wanna scrap with me," Shields said this week. "I don't think that he's that good of a boxer."

"I'm never ever going to say or even feel that Jake Paul can beat me in a boxing match because he can't."

Yes, Shields is definitely one of the best female boxers out there right now ... but many believe, even with her skillset, that she can't compete against Jake's size -- and she wants to prove them wrong.

"Any man who has a problem with that, they need to understand they can't whoop my ass either," Shields said.

But for now, Paul will fight Mike Tyson in November ... and Shields is preppin' for her July 27 heavyweight title match against Vanessa Lepage-Joanisse.

We also asked about her previous opponent Savannah Marshall making her debut in PFL this weekend ... and if there's a chance she'll do a rematch with her in the MMA world.