Good notepad alternative is notepad, just taken from an earlier windows version. Best version of it is the early one from Windows 11 though, the one that just added autosaving and tabs. It's the perfect balance of simplicity and usability for a temp note taking app imo.

That is, if you just need a program with a text field and nothing else. If you want something more useful in general though, then the obvious answer is Notepad++.