Database Size Increases

Been using this excellent plugin for some time now and really like.

Lately though been noticing that after clicking “Optimize” button my database grows in size? Not much but certainly not decreasing the database.

Never was case in past but lat month or so noticed this strange behavior. Is there something I can check to see why this is happening (like logs or something)?

Many thanks in advance!

https://wordpress.org/plugins/wp-clean-up/