ExtremeTech writes Russia is believed to be developing a new type of satellite that can chase down other satellites. This new spacecraft could be used to repair or refuel other satellites but there's also worry that it might be used for nefarious tasks such as disabling other satellites or spying on classified satellite designs or even eavesdropping on communications. Russia isn't alone with this type of satellite though, the article mentions both the US and China have similar technology.
Kosmos 2499 is most likely a proof of concept for a future Russian satellite that actually does something — such as taking photos of military satellites that belong to other countries, refueling its own satellites… or something far more nefarious, such as blowing other satellites out of the sky. The problem with doing anything malicious, of course, is that everyone with a telescope can see exactly what’s going on — so it’s unlikely that Russia would actually do anything untoward. Just like missile launches, nuclear tests, and large military exercises in the Persian Gulf, inspector satellites are all about showing the world that you can do something, not that you’ll actually do it. (Not to mention, there international treaties in place that are meant to prevent the weaponization of space.)