It’s a test of skills the babies have at certain ages, so a score of 100 would be normal, but 80 would be under developed. These babies were lacking in verbal skills, responses, etc.
I’ve heard of pediatricians giving babies certain tests to measure their growth and screening for development issues (no first-hand experience here!) as they grow, but I didn’t think they fall under ‘IQ’ tests.
I agree that the wearing of masks especially can cause cognitive issues in kids recognizing facial expressions and speech development.