@cll0d said:
Difference between watch_region and region query in discover/movie(tv)
I wonder what is the difference between this 2 options and what they actually do?

&region=
Typically used to filter release dates within a specific country.
Right at the beginning of this DOCs page you will find this explanation.
https://developer.themoviedb.org/reference/discover-movie

&watch_region=
To be used in conjunction with:
&with_watch_monetization_types=
or
&with_watch_providers=

use in conjunction with watch_region, can be a comma (AND) or pipe (OR) separated query