iCloud email stuck on "loading"

Here's what worked for me: Settings > General > iPhone Storage. This is where you probably see the spinning icon. Scroll down and look at each of the apps visible below. Find any that show a spinning icon. Remember them, then delete them. Power the phone off and re-start. The storage should no longer be stuck (although mine took a minute or two to update). If all is good, re-install the app(s) you had to delete. Good luck.

iPhone 8. IOS 14.3. It shows extra unread emails by the red badge on the home page. I reach iCloud through two different PCs. Both are Windows 10 and I use Edge as the browser. I can open email in both but the inbox just keeps flashing "loading". Both show an 10 extra unread emails in iCloud.

Yes, a couple times. When off the red badge went away but when I toggled back on, the same erroneous number came back.

On that device: email works (is current with iCloud mail) but the number of Unread emails is 10 more than actual. If I open all mail in my inbox, the red badge on the main page stays at 10. My iCloud mail: shows the 10+ unread also. But that page also has the blinking "loading" box flashing continuously. It's been that way for over 2 days now.