Interpreted as UTF-8, c3 82 is “?” U+00C2 and c2 bf is “?” U+00BF, which does not make much sense, but it’s technically valid UTF-8 data, so it should not be reported as character-level data error. Interpreted as UTF-16, it’s Hangul syllables and possibly a CJK ideograph, depending on endianness, but still formally valid data, though most probably not what was meant.
This sounds like the result of double conversion, but it’s difficult to make educated guesses. If it stands for Φ, then the UTF-16 form is 03 A6 or A6 03 and the UTF-8 form is CE A6, which don’t really resemble the actual data. Information about the origin of the data might help in guessing what transcodings may have happened.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…