This article and other articles i've read say that is the case and i wonder why.. All i can think of is the manufacturers don't want to really incapacitate the bear for hours as that would leave it defenseless if attacked by another bear. I don't care about that and i would like to have a big can of bear spray that is just as powerful as human spray.
https://johnaugust.com/2019/bear-spray-is-not-stronger-than-pepper-spray
Although pepper spray and bear spray contain the same active chemical, they are not the same thing. Bear spray has a much lower concentration of oleoresin capsicum, and should only be used as a bear deterrent.
Pepper spray is a self defense weapon intended to incapacitate human threats, and it is very effective at doing this due to its higher concentration of oleoresin capsicum. If you are serious about self defense, go purchase some pepper spray. If you are a hiker or camper in bear country, buy some bear spray.