From my understanding part of the issue is that people would use it as a test image for the sake of using Lena as a test image rather than actually picking a suitable image for their testing.

I mean also this is a scientific publication which should try to stray towards neutrality and this image is a cropped playboy still. This is blatantly not an appropriate image to use in an academic publishing not even getting into copyright issues. If you absolutely need to use a photo of a beautiful woman for your testing you could use literally any photo taken in a standard photo shoot which isn’t overly sexualized that is appropriately licensed.