He's known by many in the AI/ML community as someone who likes to slay down claims of novelty and likes to dig up connections to decades old ideas (which heavily include his own works). He's controversial, meaning that many people like him and many dislike him, few are neutral.

Perhaps look up the case with Ian Goodfellow's work on GANs. Schmidhuber said the GAN paper doesn't give sufficient credit to his earlier work on predictability minimization and was very vocal about this also in conferences (interjecting etc.).

>Out of curiosity, why would one consider him infamous?

IIRC claims were made that LeCun etc. were unfairly credited for work pioneered by him. As in, he pretty much invented modern ML but wasn't credited at all.