Drill down into the Contents/Helpers directory.Ctrl-click (or right-click) Android File Transfer.app and select ‘Show Package Contents’.Open the Applications directory within Finder.Open Activity Monitor and quit the ‘Android File Transfer Agent’ process.There’s no setting within the app to disable auto-starting so you need to manually disable the agent that ‘listens’ for Android device connections. This behaviour is fine if you only connect your Android device to your Mac for the purpose of transferring files, but it becomes a bit of a nuisance when you just want to charge your device or use it for development purposes. If you’ve installed the Android File Transfer application for OS X, you’ll find it automatically starts each time you connect your Android device to your Mac.
TL DR: If you’re not interested in following the steps one by one, jump straight to the command line solution. I can confirm it works on everything from High Sierra to Catalina, and I’ve no reason to think it wouldn’t work as expected on Big Sur too. These instructions have been slightly tweaked and re-tested on more recent versions of macOS than when it was first written.