Very easy, do exactly these two steps and classic notepad will work like before W11:
Step one, right click on start and go to Settings -> Apps -> Advanced app settings -> App executing aliases -> Toggle off notepad
Now goto start, once the start menu is opened type in notepad, rightclick the notepad and delete it
.txt files should now open with classic notepad als win+r notepad should now open the classic notepad
not sure why microsoft always need to "inovate", bring out the old version and the new version next to each other and let people easily choose which one to use, or bring a dialog in the classic version which say, if you are interested in trying out our new notepad, click here or else do not bother me again with this dialog. If people want to use an extended version of notepad, they will download notepad++ anways.
Or make it so that you can disable all the new features like tabs and resume where left when closed (ask when closing which files to save, but start always fresh when opening it), such features really needs to be able to be disabled using settings imo. Basicly notepad has not changed very much since windows 3.11 (or even before, do not know that).
Also it is or was (not sure, I do not use it anymore) quite full of bugs as you might have noticed more then once.