A screenshot is worth a thousand words.
You can add a couple of effects......
Normal mirror. Looks like a normal reflection.
Solid color overlay adjustment layer with reduced opacity then clipped to a layer mask.
Or a "shimmer" Type effect. Similar as mentioned above in how it's done. Can go any direction or be another shape.
All of the above require that you make a selection of the mirror area to be affected. Then use layer masks.
Add the layer mask to the mirror layer and then clip new layers above with the added adjustment layers.
(This is not a perfect selection...... done fast for demo and not accuracy)