Objective C two equal strings are not evaluating to equal even when the bytes are the same

Question

I have a product string:

NSString* product = models[[[peripheral identifier] UUIDString]];

and in the debugger I can print:

po product
>>> X3

and I can check the bytes:

po [product dataUsingEncoding:NSUTF8StringEncoding]
>>> <5833>

I can also check the bytes of the literal string @"X3":

po [@"X3" dataUsingEncoding:NSUTF8StringEncoding]
>>> <5833>

And I get the same output. However, when I try to do:

[product isEqualToString:@"X3"]
>>> <nil>

I get nil. What the heck!? I can understand when there is a hidden character or something, but when the bytes evaluate to the same thing, then I'm baffled.

I can even do:

NSData *d = [product dataUsingEncoding:NSUTF8StringEncoding];
NSData *d2 = [@"X3" dataUsingEncoding:NSUTF8StringEncoding];
po [d isEqualToData:d2]
>>> YES