Why did Democrats vote by mail while Republicans voted in person?

I'm not exactly saying that both groups did these things exclusively, some Ds would've voted on the day for example, I'm sure, but Liz Cheney mentioned this in her summing up of the Jan. 6th Committee findings this morning.

But if both sides mostly voted by the methods I describe, why was that? I can only imagine after what Cheney said, Democrats will be less inclined to use mail-in voting when they could be there in person like the Republicans. In either case, it was ripe ground for Trump to claim fraud, as mail-in votes take time to be counted and could be days later, as we heard all this back in the election itself.