is it true that study permits are denied if you have bad grades on your transcript?

hi. i recently heard through a friend that someone is getting deported/got their study permit renewal refused because of poor grades on their transcript. i’ve personally failed some classes, however ive shown a lot of improvement in other classes ive take. im planning on retaking the failed courses and i might need to renew my study permit in order to retake them and just want to know what my chances are