Hi,
Yes, it is not your Windows device. Yahoo Mail is down in many countries.
https://www.thesun.co.uk/tech/40732581/yahoo-mail-crashes-uk-outage/
No action is required from your end. Consult Yahoo support for exact timelines when it will be fixed.
I hope this information helps. If you have any more questions, don't hesitate to reach out. Wishing you good luck!
Standard 3rd party link disclaimer:
There may be links to non-Microsoft websites that provide accurate and safe information. Watch out for ads on websites frequently classified as PUP (Potentially Unwanted Products). There is no need to buy paid products to fix your computers, as they sometimes do more harm than good.