https://www.technologyreview.com/2024/02/27/1088154/wifi-sensing-tracking-movements/

WiFi-based human motion detection through barriers

For audio recordings, there is usually a trace of electric hum in the background that has enough randomness to yield info on when (and sometimes where) the recording took place.

It's not as much of a privacy violation as a privacy vulnerability, but it's still relevant.

Tons of websites record your mouse, keyboard, and scroll activity, and can play back exactly what you saw on your browser window from its backend dashboard as a video. This is called session replay. There are pre-made libraries for this you can import so it's super common, I believe Mouseflow is one of the biggest providers.

When a mobile app, Windows app, or even website crashes nowadays, it automatically sends the crash dump to the app developer/OS vendor (the OS often does this whether the app requests it or not because the OS developer themselves are interested in what apps crash and in what ways). We're talking full memory dump, so whatever private data was in the app's memory when it crashed gets uploaded to a server somewhere without your consent, and almost certainly kept forever. God help you if the OS itself crashes because your entire computer's state is getting reported to the devs.

Your phone's gyroscope can record what you say by sensing vibrations in the air. It may or may not be something humans will recognize as speech if played back because the frequency range is too limited, but it's been shown that there's enough information for a speech recognition AI to decode. Good chance the accelerometer and other sensors can be used in the same way, and using them together will increase the fidelity making it easier to decode. Oh did I mention no device has ever implemented permission controls for sensors so any app or even website can access them without your consent or knowledge?

Maybe this. Most smartphones have a modem inside, this modem has a separate closed-sourced operating system and it usually has the main priority in controlling the smartphone relative to the processor running the main operating system, such as Android. Sometimes the modem has access to the microphone or memory, even bypassing the CPU. Although maybe everyone already knows that.

Most modern cars are SIM-enabled and are constantly sending data back to the mothership. But even those that aren't will still collect data locally and that data will be collected when you send the car to an "official/licenced/authorized" repair shop.

If you don’t connect your Fire TV or other Amazon device to the internet it will talk to your next door neighbors Echo or whatever to send your data back to Amazon.

Well just recently learned that some printers exfiltrate data from air gapped networks through ink cartridges.

https://lemmy.world/post/37486114

Photos taken by digital cameras are also trackable in a similar way as prints taken from a printer. I recall reading they were trying to identify the device after a Harry Potter book was leaked by someone taking digital photographs.

Social graph connections can be automatically inferred from location data. This has been done by governments (example) for a long time and is also done by private companies (sorry I can't find a link at the moment).

A lot of stores track your movement through the store with the WiFi or bluetooth your phone sends out, unless you have that turned off. Since it's "anonymous" not even stuff like the GDPR requires to notify anyone of this.

Also that's going to get way worse

The worst thing about that printer tracking is that we only learned about it around 20 years after they started implementing it. It's been another 20 years, imagine what they're doing now.