Okay I found out why it changes! Apparently, the keyboard binding for quick mask is the spacebar. No wonder it keeps on changing.

I’m not sure if it’s really a bug but it happens usually when I put the ipad to sleep and then open it again, then the lasso tool creates a red “background” just like in the picture attached below. It happens also when I leave the Artstudio pro app then come back later, the lasso tool does it again when previously it didn’t.

I have managed to fix it by closing the current artwork I’m working on then reopening it again. Doing this fixes the lasso tool and it starts working normally(without the red filter thing). Hopefully, I get a response to this and maybe some clarification if it’s a bug or just a setting I have turned on.