It didn't start with the pandemic, it just continued during it.
This article from the Washington Post, in October 2019 (before the pandemic started) reported that as of then, 40% of accredited schools had already dropped this requirement.
>>> Nearly 50 accredited colleges and universities that award bachelor’s degrees announced from September 2018 to September 2019 that they were dropping the admissions requirement for an SAT or ACT score, FairTest said. That brings the number of accredited schools to have done so to 1,050 — about 40 percent of the total, the nonprofit said.
I think we have a both/and situation - there was a strong current to remove SAT/ACT score consideration already in play and the pandemic was enough to force it through at Yale and others.
What schools did not drop the requirement during the pandemic would be more interesting.
Not really. It started with the pandemic, which messed up everything, including testing.