In the biome distribution file, the Labyrinths have no restrictions on generation in the Overworld (data\dungeonnowloading\tags\worldgen\biome\has_structure\labyrinth.json):

{
  "replace": false,
  "values": [
    "#minecraft:is_overworld"
  ]
}

This leads to cases where they can be generated in the middle of deep oceans and parts of the Labyrinths appear above the ocean floor. It looks extremely bad. Screenshot in MCA Selector, where the Labyrinth generated right in the water with top at about Y = 32, and the ocean floor is around Y = 8:

At the moment, there is no blacklist for biomes in the mod's config, and the only way to prevent this behaviour is to completely override the config via datapack and specify a list of allowed biomes. Although, it should be as easy as just putting #minecraft:is_ocean as blacklist.