Can you recover a note that has been deleted accidentally?

You can definitely try.

In Notes on iCloud.com, select Recently Deleted in the folder list on the left.

If you don’t see Recently Deleted, you don’t have any notes in that folder, and there’s nothing to be recovered.

See this article: Delete and recover notes on iCloud.com - Apple Support

Check the recently deleted folder in the notes app. If you don’t find it in there, it is gone.