One big privacy issue is that there is no sane way to protect your contact details from being sold, regardless of what you do.
As soon as your cousin clicks "Yes, I would like to share the entire contents of my contacts with you" when they launch TikTok your name, phone number, email etc are all in the crowd.
And I buy this stuff. Every time I need customer service and I'm getting stonewalled I just go onto a marketplace, find an exec and buy their details for pennies and call them up on their cellphone. (this is usually successful, but can backfire badly -- CashApp terminated my account for this shenanigans)
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