Is my Murf jacked?

Recently got some used Foogers and love them. Last night I was doing some late night jamming and noticed a few things.

The last (highest) filter is not as loud as the others. Seems like this is possible, since it is a higher frequency, but wanted to ask if anyone else has noticed this.

Also, I know this is off topic, but figured since it’s “troubleshooting related”…