Most of the time, the complication is a shift of spotlight or a GM move. I get that it can ramp up the cognitive load if folks feel like they must always come up with something creative and unexpected. But I think mot complications should not be unexpected -- they should be exactly what you think would happen given the fiction, the approach and the dice. And as others have mentioned, if you as GM do not have a clear sense of what a complication looks like, maybe don't ask for a roll yet, because the stakes are not high enough for it to matter yet. Ask for the roll when the PCs' actions strongly suggest potential consequences of failure and comlications.