Robber Flies of the United States is a traditional project but it’s old enough that it still uses the “aggregator” (which we stopped supporting for new projects in 2018 but existing projects using it at that time are still able to use it). The aggregator currently runs once a day and it will add all relevant observations to the project.
So in this case it was likely a “bot” but for most traditional projects it will be a user who manually adds the observation to the project.
There’s no automatic process for this but a project’s admins/managers will see a “Find unsuitable observations” link on the project page and can use that to find observations which no longer meet the project’s requirements and remove them.