Search for documentation on how to convert/format results in MySQL.
SQL Library is returning just what it gets, and in this case was a decimal number, which is inside a tuple, the first element of the list.
It is important to understand how the values are returned. In your test you do the output to the Console, and it is shown as an object. But if you assign to a variable, you may get the converted value.
You can try:
${my_number}= Set Variable ${my_list[0]}[0]
Log To Console ${my_number}