The rear wheel cover offered here has no expert opinion/ ABE
Please ask your test engineer regarding an individual acceptance according to §21.
Basically, the releases are at the discretion of the test engineers and experts. However, they have to strictly adhere to the StVZO.

Liable
 
Components or assemblies for which an ABE or a parts certificate is required and which must be entered in the papers. Exception: If the ABE is carried, the entry is not mandatory.

Suction blanket/ brake surface/ brake pads/ brake fluid container/ brake lever/ brake lever/ brake pedal/ brake pump/ brake disc/ brake panel/ cockpit cladding/ chassis lean/ chassis steps/ suspension/ featherbone (e)/ base system/ fork/ fork/ fork bridge/ fork fan/ gear stable/ main brake level / Rear core/ rear trim/ rear wheel cover/ chain wheel (if the teeth are not identical)/ fenders/ manifolds (only if the pipe or cross-section change)/ lamp mask/ handlebar/ handlebar endblinker (for current motorcycles only in connection with the rear flashing couple)/ handlebar clamp (Riser)/ steering dampers/ air filter/ air filter insert (with a changed air flow)/ air filter box/ tire (in the case of dimensioning) pinion (with non-identical number of teeth)/ Swinge/ side stand/ secondary translation/ bench (with massive changes in the dimensions)/ disease handle/ speedometer / Tank/ Verg ASER/ carburetorials/ cladding/ cladding keel/ cladding disc

Link: https://www.motorradonline.de/ratgeber/ratgeber-dekra-gekae-kues-und-tuev-ueberlicht-landungslungtfrei-abe-co/