New 2 Glow App.. Wrongly Predicted AF..?

This is my first month TTC, so with that I downloaded the glow app & plugged in my cycle info (lengths of AF). I have always been regular since I started menstruating, 28 days exactly. I started BC 10 (something like that) months ago so that knocked my cycle off & made it variate by a few days. According to my Clue app I have been using, my period should arrive September 25th. According to Glow I’m supposed to get my period tomorrow the 20th, which makes my cycle like 24 days.

I would understand if the prediction variated by 1-2 days, but 5 days???

Also yes I checked to make sure the data entry was correct...

Thoughts below please.. thanks in advance.