It’s not so much that people will switch sides, it’s that they won’t vote at all. I know so many people who thought voting in 2016 was worthless because Trump was never going to win. Anyone who views voting as a hassle is a lot less likely to do it if they think that the results are guaranteed, so we need to be mindful that we thought that exact same thing in 2016, which caused us to get the worst president ever, and I personally believe we only won 2020 not because people switched sides, but because so many people who never bothered to vote before finally went out and did it to stop Trump.
This is how I fixed mine when it happened to me. I didn’t realize the AC was using the same air filter as my furnace, so it had gotten really dirty and blocked airflow. A cheap new air filter replacement fixed all the issues.