Besides the man and his death this effect is named after, no other topic is discussed more in the Mandela Effect area than this children’s book series. The Berenstain Bears which my spell checker shows as incorrect and wants to correct to the Bernstein bears, which is the way I remember it.
This book has changed names and there are plenty of residual evidence to show it was in fact Bernstein Bears. However any copy you will find today, even those made back in the 1970s will show The Berenstain Bears. How do you remember it?