both google.com and images.google.com allow you to 'search with google lens' directly on those two sites -- this extension overrides the 'google lens' results provided by those sites and redirects the results back to how it used to be. it isn't meant to modify the behavior of anything in particular to firefox.

for example, without this extension, if you were to go to images.google.com and click the 'search by image' camera, and upload an image, it will show google lens results. however, if you install this extension, and do the same thing, it will show results like how it used to be (and not show google lens results)