Honestly just ignore it and do your thing. It's so easy to let it get to you and taint your training experience. I let it get to me for months. This recently happened to me. Some newer, young white belts said I'm only a blue belt because I'm a woman and the coaches are easier on me (didn't even get my blue belt from these coaches and I was a white belt for 3 years) then complained when I got 2 stripes at promotions while they got 1 lol like who gives a shit about a piece of tape...doesn't give you super bjj powers or anything... then the same white belts spaz and get submitted by me then never want to roll with me again. You're probably giving them a tough roll so they're trying to talk shit to make themselves feel better because they can't handle not being the best.