(1.15.2) About the dungeons....
I was just flying around, looking for dungeons funnily enough, when I stumbled across this. I updated to v2.2.3.2 from v2.2.2.1 after seeing the changelogs about bosses not spawning twice and dungeons not spawning correctly, so I do find it humorous that I ran into this today.
I'm not sure if it was the update that caused this or what, but I must note that this is new terrain generated. Well over 2,000 blocks away from anywhere I've explored in this world, and I have not touched the config files in any way.