Hi,
Could you check that the CNAME records in Porkbun match exactly what HubSpot needs. If that doesn’t fix it, look for any funky characters in your record, like underscores or hyphens, which Porkbun might not handle right. You can use Dig to see if your DNS changes have actually gone through and are showing up everywhere they should.
Hope this helps!
Cheers,
Harsh