SenderName via GroupName

If an email was sent to a Google Group from a domain that has 'p=quarantine' or 'p=reject' policy as its DMARC policy you'll see:
" 'Sender Name' via Group-Name" <groupname@GWdomain> (the recipient's group) as the sender.

This behavior is seen so the Groups delivery system does not trigger the sender's domain DMARC policy and is correctly delivered. 

(As documented here: https://support.google.com/mail/answer/1311182?hl=en-GB#zippy=%2Ci-see-via-and-a-website-name-next-to-the-senders-name )

In the case of non Google Workspace groups, you will see:
" 'Sender Name' via Group-Name" <groupname@googlegroups.com>

See also:

• https://sites.google.com/pjrprojects.co.uk/perjurysgroupskb/privacy-concerns#h.7shm599m0kw 

• this article on Usage of discussion lists and DMARC

Further research:

https://www.dmarcanalyzer.com/usage-of-discussion-lists-and-dmarc/  

https://www.google.com/search?q=google+groups+SenderName+via+GroupName&rlz=1C1CHBD_en-GBGB998GB998&oq=google+groups+SenderName+via+GroupName&aqs=chrome..69i57j69i64.4923j0j7&sourceid=chrome&ie=UTF-8