This is pretty close to the banter I have with my male friends. I’m not bi though.
Yeah, guys aren't allowed by a lot of cultures to be as close to each other as girlfriends are allowed to be, so for a very long time many guys joke about being in love with their best friends as a way of kinda playing off how much they do actually care for each other, but in a more jokey socially acceptable way. I'm sure though that navigating that would have been extremely hard if you were actually gay, and trying to figure out if your guy friends were actually gay and into each other, or just playing around, or into you for that matter.
I lived with some roommates for a while, a couple and another single guy, and the guys were friends since HS and they and the GF always constantly joked about how her BF was going to leave her for him and other related jokes. But nah, they were just best friends, so they joked about it to kinda mask how much they really did care about each other platonically.