Regarding the very last line of your comment - I use BlockBlock (https://objective-see.com/products/blockblock.html https://objective-see.com/products/blockbloc

Regarding the very last line of your comment - I use BlockBlock (https://objective-see.com/products/blockblock.html https://objective-see.com/products/blockblock.html) on every Mac to catch/stop software installing weird startup/background agents. Might be worth checking out.