Mesh in Main level glowing if I enable sublevel

I am working on an archviz study scene and I have a main level with the house and the furniture.
The skylight is static and sun is stationery.
Then I have a sub-level with outer area with grass as well.
When I hit on play with the sub-level not added, the door is looking good, but when I enable the sub-level, it starts glowing.

The door is a BP to open and close it and the volumetric lightmap density is also high.