Only if they all died at once might give a little spike. Part of natures way of dealing with lots of food. They are the clean up crew.
Friends /family member petsitters for fish, are frequent killers of fish / shrimp and tank inhabitants, from over feeding almost always.
An experience suffered at my house before!
Now I use little pill holders (week /2 week /30 day) Dollar stores have them for a dollar and you just put all foods into the tiny compartment and for LONGER than the number of days you plan to be gone (just in case). Tape instructions on the tank.
Usually no dead creatures