ambient lighting in custom dimensions doesn't appear through portals:

if the custom dimension has a fixed time, lighting also doesn't appear correctly (blocks render as if it's day/night time in the overworld regardless of the fixed time in that dimension):

Which custom dimension are you using? Seems that you are using OptiFine, does the issue occur without optifine?

Which custom dimension are you using? Seems that you are using OptiFine, does the issue occur without optifine?

first of all, here's the dimension type:

{
  "ultrawarm": false,
  "natural": false,
  "piglin_safe": false,
  "respawn_anchor_works": false,
  "bed_works": true,
  "has_raids": false,
  "has_skylight": true,
  "has_ceiling": false,
  "coordinate_scale": 0.5,
  "ambient_light": 0.05,
  "fixed_time": 6000,
  "logical_height": 256,
  "effects": "test:custom_sky_property",
  "infiniburn": "minecraft:infiniburn_overworld",
  "min_y": 0,
  "height": 256
}

and here's that custom sky property:

@Environment(EnvType.CLIENT)
public class CustomSkyProperty extends SkyProperties {
    public CustomSkyProperty() {
        super(0, true, SkyProperties.SkyType.NORMAL, false, false);
    }

    @Override
    public Vec3d adjustFogColor(Vec3d color, float sunHeight) {
        return color.multiply(sunHeight * 0.94F + 0.06F, sunHeight * 0.94F + 0.06F, sunHeight * 0.91F + 0.09F);
    }

    @Override
    public boolean useThickFog(int camX, int camY) {
        return false;
    }
}

note that i don't think the custom sky property has anything to do with the bug, i just thought it would be worth mentioning just in case it does.

second of all, i wasn't using optifine, i was using sodium, but after testing the issue persisted even without sodium.

Probably fixed.