Back in the '00s, in the midst of the Defense of Marriage Act, the line not even the Democrats would cross was "civil unions." The reasonable thing would be to ban legal recognition of religious marriage at all and just create a civil construct that serves the same legal purpose. That was howling-at-the-moon territory. So while I'm a fan of the idea? And have been for 20 years? It ain't gonna happen in the US at least.
I have seen exactly zero evidence to back this up but I'll hypothesize it anyway - in addition to greater cultural acceptance for transgender youth, it would not surprise me to learn that an increase in dissatisfaction with gender roles and gender identity was playing a part in the increase in gender dysphoria. It's an incredible challenge to jump out of society's expectations and take on an entirely new identity. Maybe people just feel freer to do it now than they did 30 years ago? But also maybe people feel more impetus to do it because we're getting stuck.