Just wait until someone calls for an HP buff on enemies as a solution to the problem
They already did that to most Goblins lol. Goblins have 2d6 hp in the MM, some of the "boss" or guard goblins have upwards of 18-20. I think they treat them as humanoids and the higher level gobs have a few more HP. It kinda makes sense "too easy? just tack on another level to a few of the monsters.. these are the veterans"
