There's a difference between the "Notepad app" and notepad.exe. The Notepad app has the AI and all the new stuff in it. But the old C : \windows\system32\notepad.exe still exists, and is unencumbered ...
There aren't many Windows-on-Arm PCs out there yet, but when they do arrive Microsoft's Windows Notepad app will be ready for them. The freshly updated Notepad app with native Arm64 support is rolling ...