the og tags generated for thumbnail-image dimensions just contains the default thumbnail-size which is set in wordpress, not the actual dimensions of the image.
If you edit your thumbnails via WP, as you should (nobody uses squares as imgages) your rarely hit the sweetspot of 200x200 by drag and draw. So most thumbnails are not 200x200 as og loves to have.
Facebook debugger is showing the image with correct aspect-ratio at the moment, ignoring height and width-tags, but may be other sites will not?
thanks for coding!