Privacy is a problem which is getting bigger every day.

You should consider that EVERYTHING you send online is (or will be) public known. If you send your passport to an exchange to make KYC, it can leak to third parties in several ways:

-They can sell your data.
-They can share your data with their partners, who can do anything they want with it.
-They can be hacked, like ledger was.

You should really consider the risks when sending photos, comments, information about yourself, documents or anything personal online. Avoid as much as possible.

However, we are soemtimes obligated to identify ourselves and share our documents.