I agree, the character U+00B0, which would fit in 8 bits, is expressed as UTF8 as the sequence of bytes C2 B0.

I think it has to do with your string being marked as an 8-bit string and then some manipulation produces a UTF-8 string with the same sequence of code points.

The details of when string operations on mixed inputs produce wide or narrow depends on the UTF8 pragma, as does whether string literals are wide or narrow.

The more correct way to handle it is to us "encoding" functions. But I think you are getting this behavior from functions that are already written, right?