Anyone can be an lolcow. Black, white, LGBT+, etc. I know the internet is very closeted depending on said groups and it's easy to forget this, but what social media has done is given EVERYONE a platform, including fringies who speak as the loudest minorities. As a result, we aren't seeing as much as a rise in lolcows (they've always existed as people have always been weird and abnormal by society's standards) as much as we see a rise in said lolcows getting attention that they really shouldn't receive.
While some of these lolcows definitely are part of the LGBT community (In my opinion, lolcows can come from anywhere and can be anyone, it's just how it is) I would not be surprised if some people are faking it for personal gain. People can claim that there is no privilege being part of a minority group itself and I would be inclined to agree, HOWEVER there certainly are privileges for being a professional victim. The more these people whine and complain about society wronging them, the more normal people give into them to shut them up, not knowing that lolcows thrive off conflict and attention.
By adding these labels to their names, lolcows get the benefit from unsuspecting/stupid people that believe they're 100% a victim every time. It's like a get-out-of-jail free card in some cases. The more you add, the more oppressed you are, so obviously said minority group can't ever be in the wrong!
I can't even blame some lolcows for doing this shit considering how much people are so willing to suck up to them, even if they committed a heinous act JUST BECAUSE they happen to have said identity. The "smarter" lolcows catch on pretty quick and use it as a shield because nowadays people are so scared of not being PC, they'll submit to whoever will make them look the most woke.
tl;dr Some are genuine because lolcows have always existed throughout history, others clearly want the victimhood points