Recently a guest wrote a positive review for me but gave a bad rating. I got in touch with him to ask about what didn't work well and he mentioned that he by mistake gave a lower rating and wanted to fix it.
It was possible in the past for Airbnb to contact guests and allow them to edit reviews or change rating if such a mistake happened due to human error but not anymore. So caution your guests to be careful while submitting their reviews.
This another anti-host step by Airbnb just like the non chronological review order. It's sad that this is happening often.
I hope Airbnb fixes this soon as such policies impact us negatively.