I discovered SERVER-84180 when changing a current integration test to use a different metaField name. In the time-series code, we do many rewrites changing the metaField to "meta" in the buckets collection and vice versa. We miss coverage in our tests to verify these rewrites are occurring if we name the metaField "meta". From a quick glance it seems like this applies to around 20 tests, with some tests in the sharding suite as well. I asked the sharding team and they want to fix their tests separately, so avoid any in the sharding directory. This ticket should cover changing all of the tests and filing tickets for any bugs that come out.