Treasury utilizes bStats metrics, as do thousands of other Minecraft plugins and software, from PaperMC to EssentialsX. This service collects very basic data on the server which is all public, e.g., how many servers are running Treasury, how many players are online, and so on. None of this data can be pinpointed back to a individual server, they all contribute to a single pool of data. This basic data is extremely valuable for the project's maintainers to ensure the needs of Treasury's userbase are best catered for.
All of the collected data is available
here.
Should you wish to opt-out of bStats, simply disable it in the bStats config.yml file.