I'm aware of Lit and thought about mentioning some of its past versions too from the pre-spec era, but I think those are even more forgotten.

Around Angular 8-14 era Angular had a lot of "Angular is Web Components" marketing and assured devs at the time that the Angular way including CSS Modules support and its HTML Template language (and its super complex compiler) were "browser standards and the future of Web Components". Obviously none of that played out, CSS Modules are still in spec debate, the TEMPLATE tag was much simplified and no "template language" has been knighted as "the template language". But it was all so heavily marketed and it left scars in what people think of when they think of Web Components. People still expect CSS Modules. People still expect some sort of "blessed" template language out of the box for "Vanilla templating". Among other curious decisions by people marketing Angular to developers as a way to prepare for Web Components. (We can talk for hours about everything wrong with Zone.js and why it has taken Angular to version 20 to start to undo a lot of that [brain]damage.)

Lit was never quite so extreme in its worst pre-spec days, and it is useful for its templating language looked different enough from Angular's to, even at the time, prove that Angular's template language was neither HTML nor necessarily the template language to be knighted by Web Components. But it still had some versions with questionable Google-only decisions that are best forgotten today, and apparently easily forgotten today.

Of course, you don't have to take my anecdata on it, the sources still exist. If only Google made a search engine that works in 2025 maybe you could even find them.