COVID "misinformation", anti-lockdown protests, any movements that are commonly labelled as domestic terrorism (boog bois, antifa, maybe even BLM; in China it will be anything that speaks out against the CCP, etc) - the potential for abuse is massive.
Anyone that trusts the feds to do the right thing here is incredibly naive. They get to operate a black-box database; if your phone has any photos that match an entry in the db you will be reported to the authorities. I can't believe on HN of all places there's not 10x more of an outcry.