Stealth ageism. There's a local printing company near where I live famous for being the only large employer in the area demanding high school transcripts LOL. Legal or not, its a signal of old people need not apply.

I'm old enough, and grade inflation has been going on long enough, that my "pretty good" HS GPA at the time makes me look like I merely showed up for attendance compared to the recent grads. Now if they wanted a percentile instead of a GPA, then I'd have an excellent chance. But they very intentionally want a younger workforce by whatever borderline legal method necessary, so they ask for GPA...