It’s not ‘bad’ necessarily, but it makes a lot of controversial decisions such as it’s use of snap packages over flatpak. these decisions are harmful to the linux community as a whole and to the experience of using ubuntu, so it’s best to avoid supporting it.

for some context on the snap thing, basically different distros use different packaging formats (.deb, .rpm, etc.) which makes it hard to distribute software. also, each individual system is set up differently and has different packages which can make fixing bugs difficult, especially for developers who aren’t very familiar with linux. to solve this, flatpak is distro-agnostic (runs on any linux) and puts the app in the same environment on every system. it’s also sandboxed, which basically means each app is in it’s own little box and it can only see/interact with things it has permission to. snap does most of that as well, but unlike flatpak it is completely controlled by a single entity (canonical, company behind ubuntu) and it means that instead of one sandboxed thing for every distro we have two, which solves nothing. there are some other issues as well, but currently the issue of snap packages is the biggest one most people have with ubuntu.

for more information on all this, I would recommend The Linux Expirement on youtube. not by any means the only good linux channel, but my favorite. also, please ignore the tribalism. people will act like there is a best distro, there is not. people will act like a distro is useless because it doesn’t have some random tool that most don’t, it is not. if you like the distro and it works for you the it’s the best one because your use case is all that matters on your computer.