So this isn't completely true. I don't know about the other states, but in Oklahoma you still can't conceal carry without a license. You can open carry, but if you want to hide it you need your license.
Constitutional carry went into effect on November 1, 2019. It allows anyone who is at least 21 years old (or at least 18 years old and is a member of the military or honorably discharged veteran) that can legally own a firearm to openly or concealed carry without a permit
So this isn't completely true. I don't know about the other states, but in Oklahoma you still can't conceal carry without a license. You can open carry, but if you want to hide it you need your license.
According to USCCA
Link