NWEA a not-for profit research organization that supports students and educators worldwide,  reported on the effects of Covid on learning. They stated

“Children fell far behind in school during the first year of the pandemic and have not caught up. Among third through eighth graders, math and reading levels were all lower than normal”

PDF: https://www.nwea.org/content/uploads/2021/07/Learning-during-COVID-19-Reading-and-math-achievement-in-the-2020-2021-school-year.research-brief-1.pdf