This interesting article from the Bump explains it well:
https://www.thebump.com/a/matrescence#5
For a more scientific persective see:
Matrescence: Lifetime Impact of Motherhood on Cognition and the Brain
ER Orchard 1,2,*, HJV Rutherford 1, AJ Holmes 2, SD Jamadar 3
https://pmc.ncbi.nlm.nih.gov/articles/PMC9957969/