I've received multiple reports from different folks that Google Postmaster Tools (GPT) and Google's DMARC reporting have both been offline since sometime around October 4th. GPT is still accessible but has no data later than 10/3, and for those used to receiving DMARC reports from Google, none have been received since 10/3.
I'll share more information when known. Feel free to drop me a line if you have any updates.
(As an aside, Google has a helpful DMARC overview and tutorial for domain administrators. It's worth reading!)
[ H/T: Hagop Khatchoian, Benjamin Billon and others. ]
Saturday, October 9th, 2021 Update: Hagop Khatchoian and others have confirmed that Google is sending DMARC reports again. No word on GPT data yet; I've re-registered my domains with GPT again to test, but it'll take some time for me to be able to personally verify if data is flowing. What are you seeing?
Monday, October 18th, 2021 Update: GPT is back, more detail here.