Email return path is primary domain, need to be secondary domain

Question

Hi, I have a Primary domain and multiple secondary domains, all verified and Gmail activated.
The problem i am having is that, when i send an email from my secondary domain, the email received is being marked as spam bacause of
Return-Path: is stated as the primary domain
dmarc=fail(p=QUARANTINE) header.from=       it shows the secondary domain (that the email was sent from)
DKIM-Signature:  is showing d= primary domain

the primary domain has no problems, it is not marked as spam, only the secondary ones are.
THe SPF, DKIM and DMARC are valid and correct.
I host my domains on a private server, which has the DNS records.
The MX reccords are all correct too.
Does anyone have any idea how to get it working correctly?
It use to work fine, months ago, then stopped, not sure why.

User 17186075009201590584 · Accepted Answer

This is an issue that they make no efforts to fix