How do i add relationship count in REST API calls?

Na
Its just for the view
But under the hood its in simple letter

did you mod any controllers?

or idc plugins

Looks like that:

{{baseURL}}/specialities/1?populate=clinicians

Sould be:

{{baseURL}}/clinicians/1?populate=specialities

can you post your Clinicians schema

look like you have hasMany relation and not belongs