Upgraded iCloud notes
If thereβs an Upgrade button next to iCloud in the sidebar of the Notes app, you havenβt upgraded your notes. This means that until you upgrade, you canβt apply paragraph styles or checklists, browse the attachments in your notes, see and restore recently deleted notes, lock your notes or add people to notes.
If you upgrade your notes, you can view and edit them on other devices with OS X 10.11 or later, iOS 9 or later, or iPadOS 13 or later that are signed in to the same Apple Account for iCloud. You canβt access upgraded notes on devices with earlier versions of OS X or iOS. Also, any notes you create or edit on those devices wonβt appear on devices with upgraded notes.
When you upgrade, most of the formatting in your notes stays the same. However, any notes with HTML formatting (notes you created by copying and pasting from a website) may look significantly different.
See iCloud Support.