@boreduser1 said:
Language filter not working in the /search/movie API
I tried the following API
https://api.themoviedb.org/3/search/movie?query=dear&include_adult=false&language=en-US&page=1
But the results are returning languages other than English as well.

The &language=en-US parameter specifies which language your response will be in.
The language of the Overview, the title in your country, etc...
If you want to specify the language spoken in the movie using Search, it is not possible.
https://developer.themoviedb.org/reference/search-movie

It is possible only using Discover.
https://developer.themoviedb.org/reference/discover-movie
With the parameters &with_origin_country= and/or &with_original_language=.