Hello there, @Sixecho ...
I tested out posting a comment in the SpeedGrader to a dummy student account in my own sandbox course, and I'm not sure I understand where you are seeing the message covering up zoom controls. Here is what I see in my own SpeedGrader:

I can click on the "x" to the right of the green message, and there isn't anything behind it.
When you say "zoom", are you referring to the Zoom video conferencing software? Or, are you referring being able to zoom in and out to make your screen look bigger/smaller? Maybe a screenshot or a short videocast of the issue you are trying to describe would be helpful? (Please be careful not to share any student identifying information in your screenshots if you choose to go this route.)
Looking forward to hearing back from you soon.