Mac os is a proprietary operating system. Not open source. Not private and secure.
They are logging every keystroke, every website you visit, your bitcoin private keys, everything you write, and all that you do. All data being sent back to apple, or anyone that pays to have access to it behind closed door monitoring deals.
This is true for MacOS, iOS, windows, and pretty much every operating system that is not open source. With open security auditable code. Such as Linux, or BSD.
My best guess is that you just saw an active monitoring session. Seeing what you were up to. Either by Apple, a hacker, or a 3rd party listening in.
If you want help getting rid of MacOS and switching over to Linux. So you can have actual privacy and security. Please let me know. It is a passion of mine and I am here to help.