FBI using NSA databases without warrants -- again -- STILL
The legality of these investigations stops at without court orders. There's no exception in the 4th Amendment for terrorism, regardless of motivation or potential for violence. (If international contacts are involved, that is murkier, but even in such situations communications of US persons are supposed to be protected). It's clear that with Trump out of office, the FBI is doubling down on Spygate and political investigations.
And don't forget that the FBI has been trying for decades to smear the right in general, and Donald Trump supporters in particular, as white supremacists. Which makes me think that's who those queries are targeting.
This is not an isolated problem. Seven separate field offices were involved, meaning not just the Washington, DC group.