Apparently your phones have what's called an "advertising ID", an ID number for advertisers to track you with. But there's a way to delete/disable/reset your ID. Here's an article on it.
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A Way to Disable Personalized Ads on Mobile
4 Replies

Reply by freerunner
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There's no such thing as "disabling advertising ID", the option is just a distraction to make you feel fake security because as long as you use modern technology your data will always be collected and you always will be tracked and the ID is not needed because everything you do will get linked back to you. If you really care about your privacy and security then get rid of your smartphone because they're fundementally designed to be insecure and violate your privacy, not even a dumb phone but that would be your best option if you REALLY need one.
Reply by Lakes
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I understand that there's always gonna be things that weaken your privacy online. But I still think deleting your ad id is good advice. Sure, a dumb phone is always the better option for privacy. But like not everyone has the option, since you don't know everyone's situation. For example, someone might rely on certain modern apps like signal & orbot for activism or journalism/whistleblowing. (Edward Snowden himself literally advocated for Signal & Tor usage). Besides, I trust EFF is telling the truth, since they have been fighting for people's privacy rights in court for years now. I normally won't respond but I hate how people treat privacy online like it's this all or nothing thing.
Reply by ✶Rib𓆩𓁺𓆪Eye Black Dragon✶
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I'm going to assume this isn't just in the android phone and it's on Apple product as well. I'll try it out. Of course, like the first reply said. There's no absolute privacy with smartphones. The most you could do is to mitigate the data you could give out to these companies.
I stopped using Google Playstore and it fundamentally breaks a lot of my apps since I directly download the APKs in something like APKpure, APKMirror or an FOSS app called Aurora Store instead.
Reply by Virtual Insanity
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tracking Wi-Fi / BlueTooth signals, if this is a concern switch your
phone off and put it in a Faraday bag, or leave it at home or in your car. I say switch it off because in a Faraday bag it won't be able to get a signal and might try to counter this by transmitting on maximum power which will only drain the battery faster.