My opinion would be that if the training set for the face generator was made up of photos whose creators had asked you to credit them if you re-used their work,

My opinion would be that if the training set for the face generator was made up of photos whose creators had asked you to credit them if you re-used their work, then, yes, the generator is ethically in the wrong if it's skipping that attribution. Regardless of copyright. (And I feel the same way about Copilot.)