Young Sheldon season 6, episode 11 may have just revealed the dark reason why Mandy neither appeared nor was referenced in The Big Bang Theory. TV's #1 comedy continues to lean on its familial storytelling by actively developing Georgie and Mandy's arc, especially as the birth of their baby nears. While the arrival of the newest Cooper family member should be a cause for celebration, it would also worsen an existing The Big Bang Theory plothole.
While Sheldon is busy with his grant database project and George is having a secret affair with Brenda, Young Sheldon season 6's primary arc has arguably been Georgie and Mandy's pregnancy storyline. While the pair's future seemed bleak in the game-changing Young Sheldon season 5 finale, they have been able to set aside their differences for their upcoming baby, with the possibility of rekindling their romance in the near future. That would be great for everyone except The Big Bang Theory and Young Sheldon's already problematic continuity as it would highlight Mandy's absence in the original sitcom.
CBS may have found a way to finally address the issue of Mandy's absence in The Big Bang Theory as set up in the family comedy's "Ruthless, Toothless, and a Week of Bed Rest" episode. With just a month to go before she delivers, Mandy discovers that she has pre-eclampsia. Young Sheldon season 6 can use this to set up the dark future for the character as the disorder, if not taken seriously, can lead to the death of both mom and infant. If this happens to Mandy, as tragic as it is, it could effectively explain why she and Georgie's baby weren't even mentioned in The Big Bang Theory.
Admittedly, going this route may sound a bit dark for a family comedy like Young Sheldon, but it actually fits with the show's storytelling shift in the last couple of years. Instead of being a straight-up sitcom, The Big Bang Theory prequel has delved into more serious plotlines such as infidelity for both George and Mary, as well as more serious teenage issues via Paige's arc. Showing the realities of delicate pregnancies is in line with this more nuanced approach to storytelling by Young Sheldon.
Sadly, this means that The Big Bang Theory also ruined Georgie, much like it did for the rest of the Coopers. Young Sheldon could continue his romance with Mandy, but the established canon mandates that they don't end up with each other. Losing both her and the baby, coupled with the additional burden of taking care of his family after George's death, could explain the change in Georgie, however. The eldest Cooper kid was harsh and even spiteful when he appeared in The Big Bang Theory, which is very different from Young Sheldon's more earnest and optimistic version. Going through these consecutive losses could be the reason why Georgie had to toughen up.