By not allowing sideloading, the apps which fingerprint your device through access to unique elements of your phone (like the number of contacts & contact data,

By not allowing sideloading, the apps which fingerprint your device through access to unique elements of your phone (like the number of contacts & contact data, gps data, & wifi signals, network device exploration), makes it easier to expose those app entities sharing out your data and increases liability on Apple for failing to "police" their app store properly, over and above their existing checks. By allowing sideloading, a new attack vector opens up which reduces the liability on Apple, which is no different to what Microsoft and Google already do. Facebook/Meta are sort of excluded in some ways because theirs app store runs online on their servers and not on your device which is considered private property and brings different Govt legislations into play.