I had the same issue with my Hotmail account being temporarily locked due to "unusual activity", also since 1/9/2022. I also received the message "Usage limit exceeded. Try again tomorrow" when I tried to "verify" my account. Multiple back-and-forths with Microsoft support didn't help.
SOLUTION: It turns out that my problem was that I had too many emails in my "Send" folder! I didn't see this mentioned anywhere as a potential problem but once I deleted most of them, my problem has been solved. Just a lucky guess on my part. Here's what I did:
Go to Settings
Click on "View all Outlook settings"
Click on "General" and then "Storage"
Scroll down to the "Send" folder
On the right, under "Empty", you can select either 3, 6, or 12 months (to delete all emails in the "Send" folder that are older than that number of months).
I had over 24,000 emails in there, since I have been using this same Hotmail account for many years. It would be nice if there were a way to tell Hotmail to delete emails from the "Send" file after a year or two, the same way it deletes emails from the "Delete" folder after 30 days.
Hope this helps some of you!