OMG here we go again.
In most democracies, there are election poll watchers from the major parties, and also independent poll watchers to observe and make sure no shenanigans are going on. The Democratic and independent poll watchers would've reported any election irregularities. I not seeing widespread reports of such.
States run elections, even safe blue states shifted 10+ percentanage more red.
So my conclusion: The vote count itself is probably legit.
The real "rigging" was done via unlimited political spending legalized by the Citizens United ruling to unfairly buy propaganda spreading lies. That, exacerbated by inflasion, voter apathy, democratic party incompetence, voter roll purges, and most important of all: Human Stupidity. And this timeline is the result.
Think about all those people getting scammed all the time. You see those stories and be like "OMG how can they be so stupid". Well this is the same, but with politics and elections. Talk to people and you'll see how dumb they are. Some people genuinely think that fascist coup plotter will fix things. 🤦♂️
These elections (like the one OP is talking about) are election has lower turnout, so it probably favors democrats, since democrats are more energized to vote after the defeat last november.