Like Colbert stated above, I too have seen many reports of Debris being weird and not destroying Instances at all, you should use :Destroy() yourself, if you want an instance to be destroyed later you can use:
task.delay(1, function() -- The number 1 is the time it will wait before destroying it (seconds)
instance:Destroy()
end)
This also doesn’t yield the script at all, just like Debris Service.