Before you install, Greasy Fork would like you to know that this script contains antifeatures, which are things there for the script author's benefit, rather than yours.
This script will inject ads on the sites you visit.
The author of this script explains:
There will be no ads by default, the script disables all ads in the game. If you like the script so much that you'd like to donate but don't want to spend money, you can enable a setting that will replace the ads on MooMoo.io with new ads that will be used compensate all the developers who collaborated on this script.