Welcome to the Great Tectonic Shift. I think John McWhorter (linguist at Columbia, I'm a fan of his podcasts) said it best when he described himself as a "cranky classic liberal" who now finds himself a centrist-verging-on-conservative, because the whole terrain shifted underneath him. I'm GenX and pretty staunchly independent, but I've experienced a similar sensation -- my basic ethos is the same, but I'm labeled very differently now by detractors.

I've been trying to put together some kind of mental narrative around how all of this changed so suddenly . . . some r/GC users helped fill in the blanks recently. Mini data-set:

• Social media goes mainstream, 2008-ish

• Obergefell v. Hodges (LGB marriage equality), 2015

• Caitlyn Jenner comes out as trans, 2015

There seems to be a general feeling that 2015 (in the US) was the year that TRA and ideological purity really leapt to the fore in media and liberal online spaces. The alarming part, as you mention, is that critical thinking seems to have simultaneously gone down the shitter, and there's this naive sense that "only the Right can be authoritarian" (Stalin much?) and other baseless weirdness.

I'm hoping it's mostly a novel combination of social media saturation and righteous idealism. But as it's affecting health policy, research, and now (in a very visible way) women's rights and free speech and publishing and God knows what else, screw it.