It's always a shock when a perfectly pleasant family event goes sideways. These days it doesn't take much to set people off. The world has changed with the pandemic and individuals aren't always behaving at their best level. The country is divided and certain subjects should probably be taboo if we want to sustain a peaceful gathering.
Grandparents, who understand the dynamics of boundary importance may have to set the pace. Probably a good idea to stay away from heated political arguments. Sometimes that's all it takes to lose access to the grandkids as well as the rest of the family.