For me it was by watching Junjou Romantica in Youtube when I was 16. I mistook Misaki with a girl and I thought it was shoujo. So, it was a real shock for me, I didn't even know yaoi existed in general and I was super innocent even at that age. Anyways, at first I felt disgusted (I grew up in a quite homophibic family), but after that shock I became curious and kept watching. Now I only read yaoi lol.
I got an ad on YouTube. I think YT knew I was on Webtoon because that was the only thing I was reading mangas/webcomics on, then I guess it decided to show apps similar to Webtoon, but it wasn't Lezhin and that is how I got into BL. (✿◡‿◡) reply