Ask HN: Stopping Gmail-Originated Spam?

80% of spam - mostly phishing - that slips through my filters these days originates from hacked Gmail accounts. The other 15% from hacked Office 365 instances with the last 5% coming from compromised AWS instances. I seem to have had some success reporting these to Microsoft and Amazon, but no such luck with Google, and I am being inundated with them. Google's abuse report form is a dead letter box, a useless elevator button, and is probably read by AI anyway, if it's read at all.

Any ideas how to stop this? You can't filter Gmail-originated traffic because by having a partial monopoly over email means they are too big to filter (and spammers know this).