Pregnancy?

Just curious on how this works. So I am on birth control. I know I’m not pregnant I’m just wondering. I’ve been told that you can still bleed during your placebo week and still end up pregnant. This was told to me by the person that prescribed it to me. And I had also messaged a maven provider and they told me that it wouldn’t be likely for me to have a period on the placebo week if I was pregnant (which I know I’m not) but I’m just curious because I’ve been told 2 different things about it.