On Thursday morning, July 24, many Yahoo Mail users started facing issues with logging in and accessing their emails. The issue began just after 9 a.m. EST, and reports suddenly spiked from almost zero to over 9,000 complaints, as per Down Detector. The real number of people affected is likely much higher than what was reported.

https://economictimes.indiatimes.com/news/international/us/is-yahoo-mail-down-thousands-of-users-report-temporary-error-15-and-email-access-issues/articleshow/122887221.cms