They usually claim the Canadian law that supposedly “protects pronouns”.

Which is a right-wing propaganda whistle, perpetrated by people like Peterson.

The law does not actually say that, though. It is an anti-bullying law. It only gives the ability to sue someone based on being called something you do not want to be called. It does not mean you will automatically win.

If someone kept calling you “asshole”, even after telling them off. You have some grounds to sue them. But a judge will still look at the claim to see if it is reasonable.

No judge will fine someone for calling someone by the wrong pronoun once.