Well duh you might say but I usually have a policy of no Facebook-related apps at all on my phone. Not long ago however I purchased a Occulus Rift headset for my kids and at some point installed the app for it on my phone. I never logged into it and ran it once but didn’t go further than that, eventually using my daughter’s phone instead to actually set the headset up.
I do have a Facebook account that I haven’t touched in years. Sometimes, I get the occasional email from Facebook in my spam folder with friend suggestions or the like. I just ignore it usually.
The other day I started with a new therapist which involved having to meet them at a pool for hydrotherapy. Lo and behold there’s a friend suggestion within 24 hours for my therapist in my email.
You better believe I double checked my phone and removed that spyware. I am shocked how insidious their tracking is though, even though I didn’t really use their app it still knew exactly who I was and sent them information that I certainly didn’t consent to. Fuck Meta and Facebook.
The app requires location services for pairing with the service. I’m betting it uses them for a lot more then that (though you could set permissions to “only when using the app” and prevent the app from starting automatically).
If your therapist has a Meta app, it knows you both arrived at the same place around the same time and stayed for some duration. It’ll use that for friend suggestions.
The good news is, it probably doesn’t know much more about your relationship than that, and it probably suggested a bunch of other people that you ignored because you didn’t recognize their names/faces, but yeah it’s very creepy and intrusive as fuck.