Did you add any of those plugins recently? People sometimes take copies of popular plugins and publish them as their own, but with malicious scripts in them.
Have you loaded any free models from the toolbox and then deleted them? There may be a script loaded in at the same time, but not inside the model itself.
You can search for all scripts in your game by typing Classname:Script in your Explorer Search tool. Even if the script has been renamed.
I’m wondering if it’s a Roblox core script that’s located inside the ServerScriptService that you’re not supposed to have access to?