As per this paragraph:
To unlock a note, you need to enter the password that it's locked with. If you forgot your notes password, Apple can't help you regain access to your locked notes. You can create a new notes password or use your device passcode instead, but this won’t give you access to your old notes.
extracted from the support article that led you here, you won't be able to access that protected note, sorry.
If you'd like, please submit your request/comment to Apple directly, using this link:--> Feedback - Notes - Apple
Regards
Giulio