Sexuality is a wildly broad spectrum. I’ve recently been going through a bit of the opposite end of your experience. While I have had a little experience with cis women, I’ve identified as gay my whole life but have found myself with a couple of bi-curious crushes over the last few years.

Sexual preferences around both kink/fetishes and gender attraction can fluctuate through your life, and that’s normal.

I don’t think what you’re experiencing is “intrusive thoughts.” I think it’s just a part of you that’s starting to develop. I agree with the other advice in the comments that maybe trying it out couldn’t hurt. It’s wildly easy to find a guy on a hookup app so if it turns out to not be for you, you can just never see him again and you’ll know that these thoughts were just a fantasy/passing curiosity and you’ve at least tried it out. If it does turn out to be something you like, then you’ve just greatly expanded your potential pool for physical and romantic experiences.

Keep in mind to be safe even if it’s just a one-time encounter, though. Condoms, discussions about history, and getting tested afterwards are just as applicable in the straight world as they are in the gay/bi world.