Extensions in the Notes app

Hello! I'm reposting an unanswered question from 2018 because my MacBook Air (macOS Big Sur 11.6) is currently having the same problem. Thanks in advance for any help!

"Hi,

I'm curious about the Extensions menu in Notes app. It has '4 new' next to 'More...' but when I click on 'More' I'm taken to Extensions Preferences, and the Markup extension is displayed, but it is alone in the right hand pane. There is no mention of anything new. Also, when I return to Notes, the word 'new' remains.

So a bug ... but where should I find these 'new' extensions? What might they be?"

My pic: