"For nearly four years Yale’s undergraduate admissions process has been test-optional. The experience, originally necessitated by the pandemic..." https://admissions.yale.edu/test-flexible
"I am writing to announce that, due to the ongoing COVID-19 pandemic, our office will be suspending our usual SAT/ACT testing requirement for the coming application cycle." https://mitadmissions.org/blogs/entry/we-are-suspending-our-...
"When Dartmouth suspended its standardized testing requirement for undergraduate applicants in June 2020, it was a pragmatic pause taken by most colleges and universities in response to an unprecedented global pandemic." https://admissions.dartmouth.edu/apply/update-testing-policy
The primary explanation I have heard both in the news and from friends in admissions departments for so many elite schools going test-optional at the same time was for the pandemic, and most of the ones I am aware of explicitly called it a temporary measure as Yale did.
Now I could buy that the testing debate may have played a role in why some schools have been dragging their feet to return to requiring tests post-pandemic because anti-test folks are exploiting this opportunity. But having worked in academia I also would not discount the immense inertia in university admissions playing an equally large role.