Facebook recommends patients with a psychiatrist's number on phone friend one another—outing them to each other. 

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Worst, Facebook's privacy insensitivity with phone metadata compromises WhatsApp & Two-Factor-Auth; but both are is essential for security.
With more and more apps FB gets more and more opportunities to collect metadata (FB/Messenger/Whatsapp/Instagram/Lifestage/etc).
one solution would be to denote numbers as "sensitive" in FB... or opt out of being connected by them
Backwards. The doctor can have 1 work phone with no FB installed, but FB will find the doc's work number from the patients' phones.
.@zeynep @Trojan7Sec Also trans kids. Can NOT get burners.
Parent:"Huh, who is this trans specialist? My kids is just weird, not... OH..."
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