shadow slimes whyyyyy

i love this game to death, get tired of a area move on, need a specific plort, its but 2 steps away, than we get to shadow slimes, who in the 9 slimes thought "yea a non passive slime grind requiring hundreds for one door what could go wrong" its so badly balanced its another one of those traps games that are fun fall into where you get comfortable start enjoying it than they hit you with a acme rake saying now grind no fun past this point, just why, who was in charge of balancing this