The ornamental design for a displayappliance vent pattern, as shown and described.
FIG. 1 is a top perspective view of a display appliance vent pattern, showing our new design;
FIG. 2 is a top view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof; and,
FIG. 5 is a right side view thereof.
Portions of the display appliance vent pattern shown in broken lines form no part of the claimed design. Portions of the display appliance vent pattern shown in broken lines form no part of the claimed design. The plane upon which the circular features that form the vent pattern sit forms no part of the claimed design.