The ornamental design for a protective facemask, as shown and described.
1. Protective face mask
1.1 is a perspective view of our new design for a protective face mask.
1.2 is a front view of 1.1.
1.3 is a back view of 1.1.
1.4 is a left view of 1.1.
1.5 is a right view of 1.1.
1.6 is a top view of 1.1.
1.7 is a bottom view of 1.1.
The dash-dash lines in the drawing represent stitching, which is part of the claimed design. The features shown in dot-dot lines show portions of a protective face mask that form no part of the claimed design.