It is unclear to me how a domain with DMARC sp=reject; will affect subdomains. I understand that it means subdomain messages with failures should treated with a reject policy, but does it override the DMARC p=quarantine; policy of a subdomain?

Consider this
DNS DMARC record example

Should I expect that messages from next.example.com with failures be treated with a quarantine policy? Or should I expect they be treated with a reject policy?

I expect the subdomain configured in the DNS to apply a quarantine policy to email with failures. I expect any subdomains that are not configured in the DNS to fall back to the primary domain’s reject policy. I am seeing emails with failures from the subdomain configured in DNS being treated with a reject policy. I am trying to understand if this is the expected behavior of sp=reject; on the primary domain.