Configure Native Notes.app to Use Monospaced by Default For every carriage return on a monospaced line, the following line resets to the default Body format. I used this post as a reference but everything's outdated and I don't find anything  else recent out there. What are your suggestions? Thank you in advance.
It’s currently not possible to set new notes to default to monospaced.
I’m not able to reproduce your issue though; if I choose monospaced from the format dropdown then return will keep the monospaced formatting until I manually choose Body formatting again. Check your OS is up to date (I’m on Big Sur 11.3 and iOS 14.5 and don’t have a non-beta install to test).