The quantity and quality of environmental stimuli and contexts are crucial for children’s development. Following the outbreak of SARS-CoV-2 (COVID-19), restrictive measures have been implemented, constraining children’s social lives and changing their daily routines. To date, there is a lack of research assessing the long-lasting impacts that these changes have had on children’s language and emotional–behavioral development. In a large sample of preschoolers (N = 677), we investigated (a) the long-lasting effects of changes in family and social life and in daily activities over the first Italian nationwide COVID-19-pandemic-related lockdown upon children’s linguistic and emotional–behavioral profiles and (b) how children’s demographic variables and lifelong family characteristics moderated these associations within a multiple-moderator framework. Our findings showed a relationship between the time spent watching TV/playing video games and affective problems that was moderated by the number of siblings. Our findings showed that children who could be at high risk in more normal circumstances, such as only children, have been particularly harmed. Therefore, assessing the long-term effects of lockdown-related measures and how these could have been moderated by potential risk/protective factors added significant information to the existing literature.