At least those that have evidence (which many do) and allow things to go through the courts. All the way.
Millions on the Left never accepted 2000, 2004 and 2016. Millions on the Right are not going to accept 2020. We should once and for all dig into claims and run them to ground. That's the only way to build confidence in the system.
If nothing else, we can discover ways to improve the system. At the very least get the voter lists cleansed.