Default installations of Linux distributions mount more filesystems than they used to. This is because of loop devices, cgroups, and, in Ubuntu, snaps. As a result, the output from GNU df(1) as well as from lsblk(8) and mount(8) is more difficult to understand at a glance.
It is possible to make the output of these commands more readable by removing some of the “noise” devices. The following is a list of command arguments that remove irrelevant devices. After the list, I show how to replace the default commands in fish. You can adapt the replacement script for other shells.