Invalid json response laravel api’s

I have written the api`s for mobile applications in the laravel framework. I deployed my code on the domain for a few days API’s worked fine but after a few days I received javascript tags in the response due to which my application crashed or not performed correctly, I have been facing this issue for many days but I did not found any proper solution to resolve this issue. Recommend any best solution that solves my problem permanently.

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I have attached the postman json response screen shot