[OIS issue] 3x telephoto camera vibrating and buzzing in video

I see this issue happen fairly often in my repair shop and it's most likely the camera itself that needs to be replaced. Seeing as you're still in warranty, I would just have apple take care of it. If they won't you could fix it yourself or have a trusted shop perform the repairs. Not sure about other countries, but here in the US you can order an OEM camera from the self service repair store. It'll come with the parts you need and you can rent the tools. By ordering it from the self service repair store it'll allow you to reprogram the new camera. Just be aware, while this is illegal for apple to do, they may void your warranty should you, or another third party perform the repair, despite using OEM parts.