This is one of the shortfalls with DMARC and mailing lists. The only way to fix it on our end is to stop using the author's email address in the "From:" field. I don't know if there's any sort of alternative to tag emails so we actually know who they're from other than the "From:" header.

You can see the issue in the headers here:

Authentication-Results: mx.google.com;
       spf=pass (google.com: domain of talk-bounces@gtalug.org designates 2600:3c03::f03c:91ff:fe50:ea0a as permitted sender) smtp.mail=talk-bounces@gtalug.org;
       dkim=neutral (body hash did not verify) header.i=@gmail.com;
       dmarc=fail (p=NONE dis=NONE) header.from=gmail.com

I think it's worse with Yahoo email as they have the DMARC policy set to reject emails that don't pass instead of a soft fail (which means it can tag it as failed but let it through any way).