A very short entry here for an ever-present issue with Powerpoint.
When drawing lines or arrows in the software, and particularly when letting said lines or arrows snap into position, they aren’t quite aligned right. They’re visibly off-center. In short, they look terrible.
This problem has existed for years. The solution is to ensure that either the width or height (for vertical or horizontal lines, respectively) is exactly zero. In Powerpoint, right-click the offending line and select “Size and Position”, then adjust the corresponding height or width value to be zero.
I don’t like posting about Powerpoint problems and solutions, but these issues and the software itself are still all too common in academic circles.