I mean, are Republicans restricting the autonomy of these districts?
What do you mean by restricting autonomy?
Are Republicans infiltrating the DNC to make it more difficult for only their constituents?
In a sense. Consider that racial and ethnic minorities are statistically less likely to have photo IDs. They are also less likely to vote Republican. Similarly former felons are less likely to vote Republican. Ergo the GOP has an interest in mandating photo ID or restricting votes from felons, so those people who are more likely to vote Democrat do not have the opportunity to do that.
Another example: before 2020 most of the U.S. voted in person. However this year a lot of people did not want to vote in person due to coronavirus fears, and most people that were concerned were Democrats. So everyone knew Democrats would largely choose to vote by mail. Therefore Trump has pathetically tried to claim that mail-in ballots from states like MI or PA would be fraudulent because he knew they'd likely be votes for Dems. However he wanted all of the mail-in ballots from Arizona to be counted because they were likely to go in his favor. Arizona residents usually vote by mail and tend to vote Republican, so he didn't want to silence THOSE mail in voters -- he only wanted to silence and call "fraudulent" the votes he assumed would go against him.
Are the Democrats incompetent? I'd like to know what's going on here if anyone cares to explain.
I don't get what this rhetorical question is supposed to imply. If you're asking why some people can't get ID, I feels you, and I don't mind voter ID laws. But there are other ways the GOP tries to suppress votes as well.