If you have enabled DMARC, DKIM & SPF and are getting DMARC Aggregate Report emails sent to yourself which contain the gzipped XML attachments.

You can view them in a nicely formatted GUI by uploading them to Dmarcian https://dmarcian.com/xml-to-human-converter/

Email Authentication setup in Microsoft 365

https://learn.microsoft.com/en-us/defender-office-365/email-authentication-about#how-spf-dkim-and-dmarc-work-together-to-authenticate-email-message-senders