A degrader is a person or thing that makes something worse or lower in value or quality.
The word degrader can make people think of negativity or making things not as good as they were before.
Examples:
The degrader made the picture look bad.
The rain was a degrader for our picnic.
The degrader took away all the fun.
The degrader turned the happy day into a sad one.
The degrader made the cake taste like mud.
The degrader made the toy break.