The most unfair part is that most people who are going to bother leaving a private review are the ''unsatisfied'' ones while the happy clients will usual leave the public review + a generous tip and go on with their life, not saying this is the case for everyone but as a buyer myself I have never submitted a private review, all what mattered to me is that the seller felt appreciated, specially when fiverr used to inform people that the private reviews are just for the team itself and not for the seller.
That leaves you with this formula as an example:
100 satisfied customers: 80 of them rated you 5 stars and even tipped but never bothered with the private review, 10 didn't bother with any review system and just thanked you in inbox, 10 left a good to great private review
20 satisfied customers but they still thought the job could be better, left a 5 star review as a nice gesture but wanted to express more in private.
Result: 20 bad/moderate private review against 10 good/great private reviews.
Success Score after Being affected by Client satisfaction: 4-5/10
Just my two cents trying to figure out how I had fiverr's choice badge and level 2 months ago and now I'm level 0.