I’m in my late 20s. I got a bad grade (C- and only by the skin of my teeth) and several mediocre grades in high school.
I’m now in a top phd program in my field.
My in-laws try to be WAY over-involved in our lives and even they have no idea what my grades were like in high school.
No, no one cares about your grades once you’ve graduated and started whatever the next phase of your life is.