Notes not syncing to newly set up iPhone 12 mini

I got a new iPhone 12 mini on 24/Dec and set it up via iCloud backup by bringing it close to my iPad Pro. Everything synced perfectly (including Notes) except Safari Tabs from my Mac and iPad Pro would not show up on the phone, nor would Tabs from the 12 mini show up on Mac or iPad.

I waited few days thinking that the Tabs would eventually sync. But yesterday since they still had not synced. I turned off Safari syncing in iCloud settings on the phone, waited a while, and then turned on again. The Tabs still did not sync. So I then signed out of iCloud on the phone, waited a while, and signed in again. And now, in addition to the Tabs still not syncing, I was dismayed to see that my Notes were not syncing to the phone. There were no Notes on the phone at all. I left the phone as it was overnight and today morning found the Notes are still not syncing.

So I did a full erase and restore of the phone, and the find the Notes are still not syncing. All I see in the Notes app is a iCloud folder with 0 notes and a "loading wheel" going round constantly.

FYI

I am signed with the same iCloud ID on all my 3 devices: Mac, iPad Pro and 12 mini.

Mac is on 10.15.7 Catalina, and 12 mini and iPad Pro are on iOS 14.3.

All my notes are stored in iCloud. No notes are stored locally on any device.

Any suggestions on what else I can try? I would be most grateful for any suggestions.