Why so much fluctuations in percentile predictors?

Cr@cku IMS Time Career Launcher Physics Wallah Unacademy

All of these are reputable sites but why there is so much difference in their predictions?

Cat 24 was easy compared to 23 but it was really on the tougher side, if we compare it with 21 and 22. Cr@cku especially is just demotivating students at this point. I have seen countless people in this subreddit with scores of 80+ being reduced to 90-92 percentile by c@acku.