Thank you for sharing your experience. I never distro-hopped much, but still got to try Ubuntu a few times while always using Debian Testing. After a point, I had all the things I needed on Debian Stable and the few that I needed, I learnt how to use backports or makedeb etc. Kubuntu is pretty great. My own Debian journey was probably like Lubuntu > Mint > Debian Testing for a long time > Debian Stable rest of the life. If it works for you Kubuntu is still great. No need to switch to Debian unless there is a strong reason.
As for flatpak and snap, I have my reservations. I go out of my way to avoid them and find either packaged version or try the source install. However, I am not completely averse to them. I still think if someday I need flatpak only software in my workflow, I would have no qualms to use it.
Yeah, I got the understanding from another comment on here. I will put it in my list to research.