Snaps are basically Ubuntu’s private app store, and flatpaks (the supported method of app distribution by almost every other distro are not supported); there’s no tiling WM built-in for large monitors; the kernel is not kept up to date (i.e. improved hardware coverage and support); some things like streaming with OBS studio and Steam don’t work out of the box (this may have changed, but it was the case for me about a year ago).