Collegeboard released some stats.

Over 90 percent of Common App member schools are test-optional, but the Common App is seeing a slight increase in test score submissions this cycle.

% of applicants reporting scores
2019-2020 81%
2020-2021 50%
2021-2022 55%

But when the Crimson at Harvard did a first year student survey of class of 2025, they found over 70% had reported. So they took kids that reported, more likely, than did not.