It's Debian-based, but Canonical has been really Microsofty about its development. They now have Snap as a universal packaging format, and have mandated that all official Ubuntu flavors (so X/K/Lubuntu and others, but not derivatives like Mint) must include Snap, and must not include Flatpak in the default installation. They've also fucked with APT where installing certain packages, like Firefox, would first install Snap and then the application's Snap package, without even telling the user. They've had some controversy with Amazon ads in the search results, and advertising Ubuntu Pro in the fucking terminal. The default GNOME desktop also has a ton of issues.
I, and many others, recommend against Ubuntu. Linux Mint is the most commonly recommended "just works" distro. That being said, switching to Ubuntu, if able, is still preferable to staying on Windows.