The Optical Department at Walmart must have run out of blue AR contact lenses.
I noticed how he fidgeted with his jacket, and on his front right side, masked from Trump, there appeared to be a wire running vertically up beneath his jacket in front, concealed by his right jacket breast flap.
After fidgeting, he then tended to shift his glance more leftwards away from Trump, but appeared to be concentrating upon somebody coaching him, then he began to speak.
Trump had requested inspections of both candidates before the debate and the Democrats refused to allow Biden be inspected.
IMHO, they are using hi-tech to coach Biden throughout the debate, and the only thing they can’t handle is on-the-fly debate by Trump, which is too quick for them to respond in their coaching of Biden.