I don't care what some distro snob thinks.. I use ubuntu and have few problems. I replace the snaps and move on. I've been using Linux longer than most of them have been alive. They can pretend that makes me behind the times but somehow I always seem to be ahead of them.
Having made my stance clear.
Switching Firefox from the apt repo to the snap is one of the things I did when using KDE Neon on my laptop (on my desktop with Nvidia I did the opposite on Kubuntu).
I don't know what you mean about VLC though - while it's available as an official snap published by VideoLAN, it's also in the apt repos on all Ubuntu versions.
Its probably fixed now but for years vlc suffered from several bugs on ubuntu the worst being it launching multiple windows despite having that disabled in settings. I started using the PPA and now I just skip ubuntu maintained versions.