System76 edits firmware to enable S3 sleep on their machines. S3 sleep uses less power than Modern Standby.
I'm unaware of how much access Framework has to the underlying firmware blobs. If they don't have source/license/keys/etc for the right parts, they might be at the mercy of their own vendors for S3 support.
The oldest AMD chip framework sells is two generations, and to me knowledge don't have S3 support.