It is not that difficult to crack a Power Bi Interview. It is extremely easy but the only thing you have to focus is on the basics of Power Bi. If you are good at basics then no one can ever make you wrong and not that tough to crack.
If you don’t know something, good to accept that you don't know but it is your responsibility to ensure the interviewer that u you are willing to learn new things and keep yourself updated in the Power Bi field.
You can check out this blog on Power Bi Interview Questions for more frequently asked questions in an interview with simple and lucid explanations.
Also, you can watch this video for more information: