Young Sheldon is infamous for its lax approach to continuity but has also resolved some of The Big Bang Theory's burning questions. As an expansion to The Big Bang Theory franchise, Young Sheldon functions as an origin story for Sheldon Cooper. The prequel tackles an exciting time when he was still living with his family in Medford, Texas, as he deals with the increasing changes in his personal life. Despite the many plot inconsistencies between the shows, CBS maintains they are still part of the same reality.
https://screenrant.com/young-sheldon-big-bang-theory-plot-holes-solved/