Hello there @AkashHarihar!
Don’t worry, nothing’s wrong with your model. You are just encountering a troubled interaction between Nanite and translucent materials, affecting other users in the community.
At the moment, Nanite can’t support translucent in the same mesh. When a material like that is added to the setup, the mesh reverts itself to it’s fallback mesh, which is a heavily reduced geo model for rendering at long distances (think about a very aggressive LOD).
The most usual fix for this, is to separate the car’s glass into a different, non-Nanite mesh, which will leave the car’s body alone, and won’t affect your current setup. If that’s not possible, maybe due the glass geo being too incorporated into the mesh, you would have to disable Nanite for the whole car body.
Alternatively, you can try using an alternative glass material, set to Opaque, and fake the transparency effect using fresnel or reflections nodes. But at the end of the day, the best approach will definitely be separating the glass from the car’s body.