TL;DR: Nothing's broken and there's no setting to change. Your events are arriving.
This one shows up in Events Manager under Diagnostics, usually pointing at your ViewContent and PageView events, saying your server isn't sending the necessary user_data parameters. Meta didn't reject anything. It's asking for stronger identifiers, not reporting a failure.
What we send
On every server-side event we send the visitor's IP address and browser user agent, plus Meta's own click ID (fbc) and browser ID (fbp) whenever they're available. fbc only exists if the visitor arrived from a click on a Meta ad, and fbp isn't set yet on someone's very first visit, so those two aren't always there.
What Meta wants instead
A hashed email, phone number, name, city, state or zip. Those are the stronger identifiers it's nudging you toward.
Why we can't send those
People who click your Link are anonymous. They listen and leave. They never hand us an email or phone number, so there's nothing to hash. No link service can send what Meta's asking for here.
What it costs you
Fewer matching identifiers can lower your Event Match Quality score and make attribution a little less precise. It doesn't stop your events being received or your ads being optimised.
This is a separate warning from the deduplication one, which is also safe to ignore. We cover that in Testing your Meta pixel.