Why is my `git diff` now showing old mode and new mode instead of the differences in values of my local branch vs. master branch?

When I used to run git diff requirements.txt for the longest time it would show me the difference between the value of requirements.txt in my local git vs. master branch. But now when I run it, I get: diff --git a/requirements.txt b/requirements.txt old mode 100644 new mode 100755 I am so confused... Did I accidentally mess with the config?