Privacy Concerns:
Development of Ubuntu is led by Canonical, Ltd. a UK-based "trading" company which generates revenue through the sale of "technical support" and "services." By installing users agree to allow Ubuntu's parent company Canonical to collect user search data and IP addresses and to disclose this information to third parties including Facebook, Twitter, BBC and Amazon. Whenever user searches the local files for a string using Ubuntu desktop, Ubuntu sends that string to one of Canonical's servers.
Open Source Software Violations:
Ubuntu has received widespread objection from the open source community for violating free system distribution guidelines. Ubuntu's policy prohibits commercial redistribution of exact copies of Ubuntu, denying the baseline freedom. Almost all references to Debian, GNU and Linux have been removed or hidden in Ubuntu.
Deviation from Standards:
Ubuntu does not use a standard window manager. The configuration files are not where they should be. That startup scripts are noncompliant. examples to come...
Snapcraft: Starting with Ubuntu 16.04 LTS (Xenial Xerus) and later the Ubuntu system has Snap by default. In Ubuntu 20.04 there are several snap packages that replace the previous binaries and the installation of the new software gives the priority to the Snap system. Snap packages via snapd can only come from a completely proprietary server side system with built-telemetry. Read more about Snapcraft.
Alternatives:
For entry level easy to use alternatives to Ubuntu consider Linux Mint and Linux Cinnamon. The Cinnamon desktop includes a pop-up menu for launching applications and managing settings that works like you’d expect it to. It has a familiar taskbar, which can be moved to other edges of your screen. Its window management buttons are in the place Windows users will expect them. Its File/Edit/View menus work normally and are part of each window.