I didn't want hostile mobs in caves, so I edited the spawn.json of InControl to the following:

[
  {
    "mob": ["minecraft:skeleton","minecraft:zombie","minecraft:creeper","minecraft:drowned","minecraft:spider","minecraft:enderman","minecraft:witch","minecraft:husk","minecraft:stray","minecraft:zombie_villager","quark:forgotten"],
    "seesky": false,
    "result": "deny"
  }
]

This correctly prevents the spawning of all the listed mobs, with the exception of Forgotten, which spawns regardless. Hence the problem must be on Quark's end.

Modlist:
[✔] aileron-1.18.2-quilt-1.0.0
[✔] AutoRegLib-1.7-53
[✔] balm-3.2.0+0
[✔] darkness-forge-mc118-2.0.91
[✔] EngulfingDarkness-1.18.2-1.2
[✔] hexcasting-forge-1.18.2-0.9.1
[✔] improvedmobs-1.18.2-1.10.15-forge
[✔] incontrol-1.18-6.0.15
[✔] jei-1.18.2-9.7.1.255
[✔] kotlinforforge-3.7.1-obf
[✔] MouseTweaks-fabric-mc1.18-2.22
[✔] Patchouli-1.18.2-71.1
[✔] paucal-forge-1.18.2-0.4.7
[✔] Quark-3.2-358
[✔] QuarkOddities-1.18
[✔] shutupexperimentalsettings-1.0.5
[✔] tenshilib-1.18.2-1.6.10-forge
[✔] TerraBlender-forge-1.18.2-1.1.0.102
[✔] waystones-forge-1.18.2-10.1.0