This is great feature in browser. No need to juggle between browser and other tools to make notes.
Edge has something in form of collection. which is better but I liked simplicity of notes in Firefox. But one day I rebooted my PC and all my notes disappeared. I have no clue why that happened. I'm using 78esr so there was no major upgrade happened to my browser.

I see other people having similar complains but seems developers have no clue or are not interested in helping. I lost some important information in those notes. :(