I would argue a very different take on that data. We know stress reduces longevity due to weakened immune systems, higher blood pressure, and various other factors that go along with high levels of stress. I would say that it's more of the silent generation feeling comfortable with finally coming out as who they are rather than being LGBTQ+ increasing lifespan. In fact I'd say it probably reduced a lot of their lifespans due to constant stress of "being found out" along with the physical attacks that were far more common in their time.

While that's a terrible thing, I think we're going to see what the true percentage of people that identify as LGBTQ in the coming years. A good comparison is left handed people. Before it was taboo and looked down upon. After it become normalized the percentage of left handed people quickly jumped to 10% and has remained there more or less.

It wouldn't really explain why the numbers went down first