No errors in my status checks but yahoo complains 451

[bilogic]

1. MIAB is setup using box.mydomain-a.com and I added added mydomain-b.com + mydomain-c.com
2. I have no errors on my status checks for all domains
3. I sent mail using email@mydomain-a.com to my yahoo address and it arrived at the inbox
4. But when I sent mail using email@mydomain-b.com, mail.log shows that Yahoo SMTP responded with 451 Message temporarily deferred due to unresolvable RFC.5321 from domain; see https://postmaster.yahooinc.com/error-codes
5. The explanation link says

   • These errors indicate that the domain used to the right of the @ in the MAIL FROM does not appear to be a real domain.
   • We determine if the domain name exists by using an SOA query; therefore, if multiple subdomains are used in MAIL FROM commands, then besides setting up a DNS A or MX record (perhaps using a wildcard), then SOA records must be set up as well.
   • This error can be returned as either a timeout/servfail (451) or a permfail (554)

6. Found this https://wordtothewise.com/2023/05/unresolvable-rfc-5321-domain-at-yahoo/, but it was quite beyond my understanding.
7. Could it be that there is no SOA for box.mydomain-a.com?

Any idea?

[bilogic]

Unsure why or how, but it self resolved after a day. Will be wonderful if someone can explain it in more layman terms. Thank you.