Here's the last stupid bit of internet sleuthing I'll attempt on the subject:
https://steelersdepot.com/2021/04/20...laric-jackson/
Steelers depot is actually usually a pretty decent source for information on the guys they've scouted. Moreover, Jonathan Heitritter is an Iowa based fitness guy who worked with Iowa's strength and conditioning program. He references it in the article and ALSO says that Jackson is at 33 7/8.
Gun to my head, I'm saying the 33 7/8 is right and the 32.5 is wrong. There's too much about it that just doesn't pass the sniff test and the sources for the longer arm length seem better to me.