The answer depends on several things...
What is the make and model of your eBike? Bosch Performance Line CX Drive Units only exist in Gen 2 and Gen 4, not Gen 3.
Additionally, some eBikes use Bosch "design covers" for aesthetically integrating the Drive Unit, while others use custom design covers designed by the OEM themselves. I'm not quite sure which part you are referring to with "brush guard," but some OEM designs also have a bash guard in addition to the plastic design covers, usually located underneath the Drive Unit.
Can you share a photo of your eBike, or the part in question? I can provide better guidance from there.
Thanks!