If all those above are returning True then it might be worth sharing your code, as the return should be True or False if you pass each output value to the above-statement @rasjani has provided. just for further context, the isalnum() method returns True if all the characters are alphanumeric (a-z)(0-9) and False if they are not alphanumeric (space)!#%&? etc.
So in your example, Test*/-123* should return False as it is not alphanumeric, and AG9C9D91 should return True
Here’s a working example:
*** Test Cases ***
Alphanumeric Or Not - Example
@{output_list}= Create List AG9C9D91 12335666 TESTTEST Test/-123* 5879-7888 Test_testp
Log To Console \n
FOR ${item} IN @{output_list}
${res}= Evaluate "${item}".isalnum()
Log To Console Is Item:${item} Alphanumeric: ${res}
END