Crontab Operation not permitted

I have the following crontab on my mac OS Catalina 10.15.1 :

* * * * * /Users/username/Desktop/cronjob.sh > /Users/username/Desktop/cronjob.log 2>&1

Within the command file is:

#!/bin/bash

touch /tmp/foo

However I was left with the following line inside cronjob.log

/bin/bash: /Users/username/Desktop/cronjob.sh: Operation not permitted

--- Why is operation not permitted event though the permissions for cronjob.sh is set to +x?