Would an IM app server holding user's messages long after the content was delivered be an issue of personal data protection?

Take a IM app like WhatsApp. If I send a message to another user while their client is offline, the server holds the message and then delivers it when the receiver's client goes online. It even has those two blue ticks, to show that the other user read the message.

Considering an IM app like WhatsApp, would an IM app server holding user's messages long after the content was delivered be an issue of personal data protection?

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I know the answer would be jurisdiction-based, because laws aren't the same everywhere. Answers like "in the EU it is like xxxx" or "in the USA it is fine" are ok.