Vue 3. It was highly anticipated but when it was initially announced everyone including HNers were up in arms about how it's going to kill Vue. I can't find the thread but I do remember it vaguely. Thankfully the release not only lived up to its hype (faster, smaller, easier) but also put to rest almost all objections about backward compatibility. I really think the Vue team did an awesome job with their next release…
My theory was that not having the router and vuex ready on day one had hindered the hype. Maybe I've been wrong.