Downloading a pirated copy of the work. Pretty clear cut that this is illegal.
Feeding a work into an algorithm. This seems to me like it should be legal. Making it illegal looks like it would open an incredibly shitty can of worms.
Generating and distributing a partial copy of a copyrighted work. (“The AI just spat out three paragraphs of my text nearly verbatim!”) It’s unclear if this is even happening.