What is happening here? Sound design question

When I hold the key for about 1 second it’s like the filter suddenly opens or something.

What in your opinion is happening?

It is a edit to a pre-existing patch but don’t know what I done.

Just curious.

(bonus tom)

Sounds like either ENV1 HOLD or square wave LFO1 in retrigger mode opening the cutoff. My guess ENV1 hold!