Thumbnail quality - how to improve

hi there,

i am having an issue with the thumbnail quality on people tags. many pictures are too blurry and i can’t see the actual face of the person.

Trying to solve this, i must, either enter one by one in to the pictures and take a better look or CTRL + SCROLL to enlarge or reduce the size of the thumbnails.
My library is very big and finding a wrongly placed tag into a single person that has more than 10.000 tags is impossible like this. (i am trying to find and remove wrongly placed tags)

any suggestions how to get crystal clear thumbnails in "people tag " ?