So the code underpinning Copilot+ Recall includes a whole bunch of Azure AI backend code, which has ended up in the Windows OS. It also has a ton of API hooks for user activity monitoring.
Apps themselves can also search and make themselves more searchable.
It opens a lot of attack surface.
The semantic search element is fun.
They really went all in with this and it will have profound negative implications for the safety of people who use Microsoft Windows.