Somehow the mob spawning got completely fucked on my save overnight (more like over a dozen night, since I haven't played recently)
I keep having driggers wandering my base in the middle of the day. At first I thought they are just leftover from the previous night, but I'm pretty sure most of them weren't there before and they are there even on calm nights. Also there's a bowtorn in my barn every time I'm feeding my goats.
And now I peek into a random hole in the ground and see this.
I haven't installed any mod since starting this save and I don't have anything that changes spawning behavior.