How accurate is the plan payback estimator?

I feel like I’ve seen a number of posts of being surprised by the payment amounts when switching off of SAVE. Is this because the estimator is inaccurate? Or is it just shocking because SAVE was reasonable and the new plans aren’t? I am working toward PSLF and just trying to understand how accurate the estimates are to budget for my baby and trying to buy a house, and I don’t want to just sit around waiting for the official numbers unless the estimates are wildly inaccurate. Thank you!