I've got a side project still on Svelte 3, I feel this. I got the implementation into a good state a few months ago and haven't needed to touch it, soon it will be two major versions behind. No regrets, no other framework was as easy to work with for a primarily SSR app.

I was feeling this with Quarkus too, but they finally set one of their recent versions as LTS. Setting an LTS and migration guides between LTSs is a practice I'd like to see more in front-end tech.