As you can see the variables "in" and "p" have the same value,
No necessarily.
They both have the same visible string, but probably one of them either has a non visble char value, or maybe the '\0' is missing or similar.
Check if the length is the same too.

also take note of the docs:
Returns true if this byte array is equal to string str; otherwise returns false.

The Unicode data is converted into 8-bit characters using QString::toAscii().

The comparison is case sensitive.

You can disable this operator by defining QT_NO_CAST_FROM_ASCII when you compile your applications. You then need to call QString::fromAscii(), QString::fromLatin1(), QString::fromUtf8(), or QString::fromLocal8Bit() explicitly if you want to convert the byte array to a QString before doing the comparison.