Snaps are a way to build applications so that they can run on any platform with one build method. It makes it easier for developers to publish their apps across multiple different Linux distro without having to worry about dependency issues.
Snaps have been very poorly received by the community, one of the largest complaints is that a snap program with take 5-10 seconds to start, where as the same program without snap will start instantly.
Ubuntu devs have been working for years to optimize them, but it’s a complex problem and while they’ve made some improvements, it’s slow going. While this has been going on, Ubuntu is slowly doubling down more and more on snaps, such as replacing default apps with their snap counterparts.
On the other hand, other methods like flatpak exist, and are generally more liked by the community.
This has led to a lot of Ubuntu users feeling unheard as their feedback is ignored.