Solid tips. One simpler fix often works. Turn off Only Draw with Apple Pencil. Go to Settings, Apple Pencil, toggle it off. Open Notes, test strokes. If it works, turn off similar toggles in each app.
If your stylus is a capacitive type, stop pairing. Turn Bluetooth off. Write in Notes. It acts like a finger.
Restart the iPad after changes. Hold Power and Volume Up, slide off, wait 20 seconds, power on.
This solved issues for 3 of 5 third party stlyi in my tests.