Ever since upgrading to 1.14 on Wednesday April 24 I had barely to no hostile mobs spawning in the Overworld as well as the Nether. 

Overworld: Hostile mobs (Zombies, Skeletons, Spiders, Creepers, Enderman, Witches) don't spawn at night or when the light level is low enough (no mobs in caves). I spent multiple nights in a row outside without encountering a single hostile mob. If hostile mobs spawn, its about 5-10 per night. 

Nether: No hostile mobs either. 

I've restarted the game multiple times, but the problem still persists.