[avian]

No idea about Upwork, but I had about the same situation about some other company sending me mail I cared about for a reason and their mail was not getting delivered to me because their DMARC check was failing.

They said "thanks, we'll look into it" and kept sending broken mail for years.

My guess is if you're a big enough player Google learns to ignore your broken DMARC config or somebody knows somebody on the inside who can add an exception. And then your mail gets delivered to @gmail.com just fine and that means it's working and wtf is this guy complaining about.