There is a shred of legitimacy to that argument unlike all their ridiculous voter fraud hoaxes. Democrats did use Covid as an excuse to increase voting by mail which they knew would help them in the election. Luckily there are places we go to when there are disagreements. The courts agreed with the changes. There is no such thing as retroactively changing the rules though. Courts are going to upheld votes that were cast by a means provided by the government 100 times out of 100 even if the court later rules they shouldnt have been allowed to cast their vote in that particular way. To give an example, in Harris County Texas there was curbside voting usually reserved only for the handicapped that Republicans sued about and the court ordered them to stop allowing that curbside voting for everyone from that point forward. The previous votes still counted. The main difference between Republican and Democrats when it comes to intent when changing voter laws is that one side typically is trying to get more people to vote which the courts will interpret as being in the publics interest. So as established in the impeachment hearings by Trumps own lawyer, if a politician has a legit motive for doing something then it doesnt matter if they also had a corrupt intent.