Why are the Republicans finally jumping ship?

Just today, we're seeing some die-hard, dug-in Republicans rolling over, and apparently ready to throw Trump under. Clearly it's related to the attack on the Capitol last Wednesday, but it still took days to see a budge. After four years of Trump's abject lawlessness, corruption, criminality, defiance, and mania, what do you think finally may have made even the last hold-outs consider going against him?