You assume a loss of learning from the outset. I think answers are likely a little more complicated as surely there are positives to take from this also.
I don't know if are some studies about the process learning during the Covid pandemy. I read about comportamental and emotional problems in high school, gymnasium and primary level.
Students began to develop new learning skills in the adaptation phase, due to the precipitous onset of the coronavirus disease. One of these is self-controlled learning. However, I haven't come across a study on how to reveal this skill on young children.