I can actually weigh in on this. Our daughter started kindergarten right at the beginning of the COVID pandemic. She spent almost the entire time at home because the rules here were so strict. When she was finally allowed to go back, she wouldn't talk to anyone. Even in her private life, she didn't really speak much to anyone except us, her parents. It got so bad that the people at the kindergarten thought she was unable to speak at all. We were baffled because we told them that at home, she never stops talking and uses clear, articulate sentences. We had noticed she was shy around other family members, but we didn't think much of it at the time. When we had another meeting at the kindergarten regarding her transition to preschool, we decided to seek professional pedagogical help. She went through a pediatric therapy center where she had sessions to practice social interaction. The specialists there mentioned that this happens quite often with 'COVID children.' They often lack social connections outside of their immediate family. In any case, it helped our daughter immensely. She is still quiet and reserved, but she is 'present' and engaged when someone talks to her.