In fact, a crack occurs in the wall at the place where the lantern is. When the lantern overheats 
Due to the lantern overheating The cement of the wall above the lantern loosens its grip on the lantern Due to which the lantern gets cracked

How to repair a crack in a lintel on the front or side wall of a house building

1. Plastic mesh

After breaking up the plaster six inches above and six inches below the lintel above the wall, a plastic net is placed over it and watered thoroughly.

2. Line inside the Plaster

The cement applied to the lander is first carefully removed to give a line within the plaster on the lander area.
After the wall is thoroughly watered, it is first plastered with a single plaster
After it is plastered, a line is drawn inside the lantern-shaped plaster to separate the letter and wall plaster. Due to this, there is no crack in the wall.