I read an article earlier stating that the WH is using the Russia/Ukraine situation as a distraction from the US problems being caused by the Demonrats and by putting focus on war, which the article explained that if war is declared it will automatically put a stay or freeze on the 2022 elections which they know they are likely going to lose. If Congress approves war declaration they will use it to not have the election take place giving them more time to plan a way to secure their position in power. It certainly makes sense if Congress is able to stay the November election by the US going to war.
I have not heard that war would put a freeze on Congressional elections. From what I remember, elections continued throughout war time.