Not my mantis, belongs to one of the members of a Discord server I'm on. Any one know what it is? I've seen the fluid pockets on slightly mismolted wings before but not on legs. You can see the lump on the back right leg.
A bubble of hemolymph. Something went a bit wrong during the final molt and it looks like her leg was punctured a bit or something. It usually happens in the wings, but I've heard of it happening on other parts too.