Has there been any sort of MathJax update? In this answer I see the denominators in the bottom two entries of this matrix are partially cut off. I do not remember seeing this behavior before.
I just checked and my zoom is at 100%, so it should not be a zooming issue.
This is the question and my browser is chrome version 80.0.3987.132 on Windows 10.
Edit: Changing the math renderer to common html fixes it, but it still seems this glitch should be recorded.