The problem lies in what is a “depiction”. The way it is written, even cropped, rotated, blurred, or in any other way processed files of that “depiction”, would fall under the “identical” part.

Since perceptual hashing does exist, there are open source libraries to run it, and even Beehaw runs an AI based image filter, the “reasonable effort” is arguably to use all those tools as the bare minimum. Even if they sometimes (or always) fail at removing all instances of a depiction.

But ultimately, deciding whether a service has applied all “reasonable efforts” to remove “identical copies” of a “depiction”, will fall on the shoulders of a judge… and even starting to go there, can bankrupt most sites.