Too many mobs

Too many mobs. I know that someone mentioned this in the Minecraft Multi-Player discord server, although I cannot find it. I am experiencing this issue too: While in easy difficulty, there are an absurd number of hostile mobs that spawn in a tiny area. As you saw in the first picture, I killed 19 creepers in a tiny area. In the other two screenshots, you see how many spiders, skeletons, and zombies there are, and in the third you see easy difficulty. This poses a problem for survival players, and is annoying for me, as they also spawn *inside* of my buildings (in picture number 4, you see my skytrain system). I am hoping to get this second issue fixed fast, especially creepers spawning inside and destroying my hard work...

Side note: I need difficulty on so I can have guardians in my zoo.