If it turns out you wrote a bad review, you have then wrote Lashon haraa and you will join the likes of The Wolf who, by his own admission many, many times on this board is an absolute sinner since he is clearly asking people’s opinions on goods/services and putting a “stumbling block” of front of folks should they have a bad opinion of someone/something.
If its a good review, well, then clearly the restaurateur paid you off.