What sort of message would it send out to others if they had a short ban for such behaviour? The length of ban needs to be strong enough to act as a deterrent.
You think 3 years is a short ban and not a deterrent? Do you think there would be fans willing to shout a racist slur because “it’s only 3 years”?
For a frame of reference, the first Covid lockdown was 2 years and 1 month ago.