I work in the software industry in India. My coworker keeps suggesting to change the work I did. This happens 3-4 times per week.
For example, my tech lead instructed me to build a contact form, and he has allocated time for it. My coworker suggests that I add a Captcha as well. This will take more time that has not been accounted for. Besides, if a Captcha were necessary, the tech lead would have told me.
I want to tell the coworker "you mind your own business", in a manner which is not 100% polite, but it should not sound so rude either. He should get the message that I really, really don't like such interference.