550 5.7.1 Relaying denied (Firebase)

[YakameP80]

I have followed the instructions for deploying on Firebase, and I have also set up the records in Cloudflare. However, when I try to send it from my Gmail, I get this error:

"550 5.7.1 Relaying denied"

and I am not receiving any emails at all.
Please help me.

[pyonchi101]

same "550 5.7.1 Relaying denied"

[LightMatheus]

Same here... pls fix

The remote server's response was:
550 5.7.1 Retransmission denied