You're hand wavy "it's the pandemic" neglects the other evidence provided in the article that happens to coincide with the pandemic such as the elimination of test scores as admissions criteria to many universities. And the article certainly doesn't blame it wholly on the pandemic, for example here are two theories it presents:
> How did this happen? One theory is that the attention-shredding influence of phones and social media is to blame. The dip in math scores coincides with the widespread adoption of smartphones; by 2015, nearly three-quarters of high-school-aged kids had access to one. A related possibility is that technology is making students complacent. Emelianenko told me that students “are just not engaged in math classes anymore”; they seem to believe that they don’t need to learn math, because they can use AI instead.
> Or maybe students have stopped achieving in math because schools have stopped demanding it of them. During the George W. Bush administration, federal policy emphasized accountability for public schools. Schools that saw poor performance on standardized tests received increased funding at first, but if scores still didn’t improve, they had their funding pulled. Research suggests that this helped improve math outcomes, particularly for poor Black students. After 2015, however, the federal government backed off from its accountability measures, which had faced bipartisan criticism. (Some teachers’ unions and progressive parents wanted less emphasis on standardized tests, and some conservative politicians wanted the federal government to remove itself from education policy.) Many schools across the country have shifted toward making math engaging for students at the expense of evidence-based teaching practices. And due to funding shortages or misguided efforts to improve equity, many students are held back from taking the hardest math courses.