Login not working on iOS

[miloth]

I am trying to fetch data from a website through three requests:

1. GET a CSRF token cookie.
2. POST the login info.
3. Fetch the desired data.

The above works fine on Android. Yet, it fails at 2. on iOS (ver. 16.4). Basically, it returns code 200 instead of the correct 302 and the sessionid cookie is not present in the response headers. Note that the requests were tested in Postman and confirmed to behave as the Android case.

Could you please help me trying to debug this?

PS: unfortunately, I cannot share the website, since it is a private company service.