Not a huge one, but it is only free for personal and non-profit use. “If your notes contain content directly related to work projects or processes for a greater-than-one-person company, then you require a commercial license.”
Since it is on flathub and they don’t really nag you, I am sure there are people who aren’t really aware.
FYI on CUPS, Apple hired the dev and bought the code in 2007. He left Apple in 2019 and actually forked CUPS. My system it is running OpenPrinting CUPS and not the Apple one. It is still nice that they share its code it just got a little more complicated in the past few years.