As far as I know, RFID tag memory is always encoded using hexadecimal format. So even though your input is ASCII, it is written as hexadecimal. In fact, all 3 formats: A (ASCII), H (Hexadecimal), E (EPC decimal) are always written as hexadecimal to tag memory. So when you read tag data, you always read its hexadecimal value.
If you want to read the data in different format, you just have to translate it. I prefer to translate the hexadecimal tag data to groups of four binary characters(1 hex digit to 4 binary digits) and then to decimal format. And thats it.
To wrap it up - there is no mistake, this is how it works. You just have to translate the read data.
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