Tips for a face blur that actually hides identity
Cover the whole head, including hair and ears, not just the eyes. People are surprisingly recognisable from outline, hairstyle and context.
Check for other identifiers in the frame: name badges, school logos, team numbers, a reflection in a window. Cover those too.
If the face is large in the frame, use Pixelate or Black box; a light blur over a close-up can still leave a recognisable silhouette.

