Some creatures, like Black Puddings, have the Amorphous trait, meaning that they can move through very small spaces. But these creatures don't all have the restrained condition immunity.
What happens when you successfully throw a net at such an amorphous creature, provided that its not immune to the restrained condition? Will they be able to just move away from the net without any penality due to being amorphous, or will they suffer the Restrained condition as normally given by a net?
This assumes that the creature doesn't passively dissolve the net when it touches its skin, or some similar destructive effect.