Does anyone think a provider might tell client they will give discount for great review?

That is just one way to game the system.   My guess is that a lady who is just starting out may be more inclined to do that, closely followed by a lady who has had a run of bad reviews.    Now, do I factually know it happens?   No, not at all, but I would be shocked if that were not the case

she better not post it in an ad on this site, or she will likely get booted off.  What she tells you in private is between the two of you.

A 7 becomes a 9 after a few shots of Vodka. Just saying.

I wrote only a few reviews but told the provider when I stayed with her that I would like to write one.
But didn't ask for a discount nor did she suggest it.
Anyway i sent the review to her before publishing just to make sure that she feels comfortable and to correct some wrong spelling.

most common is to get the discount on the next visit.  I've never accepted though. Too much hassle to keep track of.