I don't know that I agree that it's crazy. Any time I see a base64 encoded string, I decode it, because I want to know what's in there and what I'm working with. Don't use b64 if it's something you don't want me to see. Obfuscation isn't even the point of b64, because if it were, their strings would be less instantly recognizable.

The decoded b64 just being an offset integer is like high school level programming. Of course I'm going to send whatever offset I want and assume that's what the API author is allowing me to do. Especially if I'm in the shoes of a frontend engineer, and my Jira ticket says, "design a pagination UI element that allows the user to select a page of results." Now if that Jira ticket was impossible from the API, I'm going to go to my team and ask if the alternative (the "load more" button element) approach is acceptable or if we should butt heads with backend.

Decoding b64 isn't crazy, spending billions of dollars on a super computer to crack RSA encryption on a pagination token to discover that it's just an encrypted offset integer is crazy.