That's a fake so-called Tech Support scam alert/warning which you are seeing in your browser.
"
Remember that real error messages from Microsoft, or other big tech companies, never include phone numbers for you to call them.
If your screen suddenly fills with scary pop-ups you should immediately close your browser (try pressing ALT+F4 if you can't do it with your mouse). If you can’t close your browser try restarting your computer.
"
Suggest reading:
- Protect yourself from online scams and attacks - Microsoft Support
- How to spot a tech support scam - Microsoft Support
Also see the other possibilities listed in this reply: Thread "Blocked computer" page 1: AW's reply on January 21, 2023
To prevent even seeing such fake alerts, use a good content/ad-blocker such as free uBlock Origin.