Except that in the 2020 election, the few fraudulent votes that were discovered were mostly cast by Republicans.

This has always been the case, especially in "red" states. Pheonix has trouble getting bond issues passed because such a large percentage of its population are "vacation" residents who also have residences in other states. Any attempt to get cross-checks of voter registration has been attacked and villified by conservative state legislatures, so we'll probably never know how extensive GOP voter fraud is in such states, especially in absentee voting.