I know this is a joke thread but ive wondered this before and did some research so here's an actual evidence based answer, because this is a real proven phenomenon
Conventional beauty standards like being thin, having natural hair colors, and maintaining flawless skin were built around cisheteronormative (straight) ideals.
The process of coming out usually makes people do a lot of introspection. Once a person overcomes the fear of societal rejection regarding their sexuality or gender, they often stop caring wether people find them attractive or not, which tends to lead to what you're describing
Plus, LGBT+ spaces have historically been places where people have very wide fat acceptance and body diversity so theres less pressure to lock the fuck in.
The LGBT+ community has always had roots with alternative subcultures like punk, goth, grunge etc who also practice non conformity and generally just don't care about attractiveness in the typical sense