Are decentralized services truly private?

Privacy is my number 1 priority, but I find it hard to trust protocols. Your data is valuable and they’re probably collecting those too. Even services that are known for privacy still log some information. For example, Protonmail removed the “we don’t log IPs” from their privacy policy. That is because now they do, just in case. So what gives us the guarantee that decentralized services aren’t collecting information?

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