Stop iPhone from automatically syncing with Mac?

Running an iPhone 7Plus with iOS 14.1 and an iMac Catalina. Every time I charge my phone it starts to heat up and there’s a symbol of two spinning circular arrows in the top left corner. Apparently it’s syncing with my Mac.

I look at my Mac and indeed there it is, my phone is syncing. Everything is greyed out at this time, so the only way I cam stop it is to Activity monitor, find something called AppleMobileapp or something along those lines and killing the process. But how do I prevent this from happening over and over again? I used to be able to do it when iTunes was a thing, but now that it’s gone, I don’t know what to do.