If you’re interested to work on this within yourself, of course getting professional help with a therapist would be best but you could also try some simple exposure therapy on your own. Maybe watch some shows and movies featuring normalized gay relationships. Use that to slow-drip the normality of gay PDA’s existence into your experience.

Here’s a Rotten Tomatoes list you could browse to get started. I think you might want to look for stuff where you can follow and enjoy the plot as well as see gay characters showing PDA. You can try doing this at your own pace to work on slowly desensitizing whatever cringey bit in your mind is having these homophobic reactions and messing with your ability to deal with public reality.

If you are interested in this idea I’d suggest sticking with mainstream films and avoiding porn. Even though it’s really available and even if porn in general is your thing, porn generally isn’t the best way to constructively work on your own sexual education. I think since it’s PDA you’re dealing with you’d be much better off with stuff that can teach your brain about the human side of PDA in our society, portrayed outside of the performative sex acts found in porn.