Look, just because most conspiracy theories are ridiculous doesn't mean that all of them are wrong. Especially if the people promoting the "conspiracy" are a good number of highly trained experts commenting on something within their field, as many epidemiologists and public health officials on social media are.
Numbers are artificially low across the board because, although lab tests are (as far as I know) consistently reported, self-report is inaccurate. Large amounts of people believe that Covid is a hoax, so they won't report their cases. Among those who aren't in denial, only a fraction will actually report their cases, whether because they don't know they should or because of access issues.
Additionally, I've been seeing larger and larger numbers of anecdotal reports that local governments (especially right-leaning ones) are suppressing numbers. Whether that's because they're too swamped to accurately report, or because they're deliberately trying to make us "return to normal" so the economy doesn't have to be restructured, I don't know.
What I do know is that Richmond is a relatively progressive oasis among the surrounding counties. Henrico, Hanover, and Chesterfield residents aren't politically uniform, but their representatives are overwhelmingly Republican, sometimes very right-wing Republicans.
Personally, I think it has to do with the way Covid denial and number suppression happens on a political level. I don't think it's a coincidence that the more conservative counties are touting lower numbers: it fits with their agenda.