I'll give you a plausible but hypothetical example of why I'm more worried about domestic mass surveillance than foreign mass surveillance. Let's say a person named Alice is involved in BLM, and though she does nothing illegal, she becomes a thorn in the side of the local chapter of the Proud Boys. Bob, policeman who is also a member of this Proud Boys group, happens to have an old high school friend, Candice, who now works in information technology for a federal law enforcement agency. Bob, pretending to be acting in his capacity as a law enforcement officer, pressures Candice into abusing her access to social media surveillance data to share information about Alice, and Bob uses that data to track down Alice in an isolated location and break her kneecaps.... Foreign mass surveillance is generally much less tightly coupled with regular people in the US, and while something like this story could happen, it'd pretty much have to involve foreign agents (spies) who are much fewer in number than far-right policemen.