Your profile shows using an iPhone and you unlocked the note View notes and locked notes on iCloud.com - Apple Support
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When you set up Notes with iCloud, your notes stay up to date on iCloud.com and every device with Notes turned on in iCloud settings.
The notes list contains the notes in the currently selected folder. Notes are listed by last-modified date, with the most recent note at the top of the notes list. The list shows the first few words of each note.
Is iPhone also synced with Mac , and notes box is turned on in Mac system preferences ( the notes can be visible ) in a scenario when you iCloud storage space is in designated limits , see the recent iCloud storage Check your iCloud storage on iCloud.com - Apple Support
How to check the storage on your iPhone, iPad, and iPod touch - Apple Support
In the your screen shot it says that iCloud storage is full either upgrade the storage plan Upgrade to iCloud+ - Apple Support
Or follow the article Manage your iCloud storage - Apple Support
As per the article How to lock or unlock notes on your iPhone, iPad, and iPod touch - Apple Support
Before you begin
If you're signed in to iCloud with a Managed Apple ID, you can't lock your notes.
Note : you have not deleted the notes so won't find out in recently deleted , the main reason note will not be found is the iCloud storage is full , when you add new notes they won't be saved .
This article Get help with iCloud Photos - Apple Support
What happens when I go over my iCloud storage limit?
If you exceed your iCloud storage limit, photos and videos won't upload to iCloud and your library won’t stay up to date across your devices. To continue using iCloud Photos, upgrade your storage plan or reduce the amount of storage that you're using.
Reduce the storage for iCloud Photos by deleting photos and videos that you don't want to keep from your iOS devices or on iCloud.com. Your device will immediately remove any photos and videos that you delete and they won't be available for recovery in your Recently Deleted album.
If you're out of storage, your devices won't back up to iCloud, and new photos, videos, documents, and your information won't stay up to date.