First and foremost, GOPers want to make it difficult for 'certain people' to vote and this ruling allows that voter suppression to continue.
Then, slightly off topic, there are the disparate approaches to the health and safety of Americans in this pandemic. In Wisconsin it was (properly) ruled that the Governor can use emergency powers in a pandemic and issue rules to protect the health of citizens. In Michigan a GOPer packed Supreme Court ruled just the opposite.
Sadly it's going to take a LONG time to get rid of the far right tilt currently in our court system.