The issue was caused by an error in the custom policy. Sign in orchestration step was duplicated and that caused the described behavior.
Azure B2C SAML integration with salesforce as IdP issues
I am testing B2C federation with Salesforce as IdP using SAML as in:
I am testing the federation in Identity Experience Framework by running the relying party policy with the jwt.ms set up as a reply URL. I am redirected to the Salesforce login page, Salesforce though, when successfully logged as a salesforce user, redirects me to the https://your-tenant.b2clogin.com/your-tenant.onmicrosoft.com/B2C_1A_TrustFrameworkBase/samlp/sso/assertionconsumer page (which is set up as ACS URL in salesforce. Where "your-tenant" is obviously my tenant name), where I need to log in with the B2C user which kind of defeats the purpose.
I expected to receive the B2C Token displayed in the jwt.ms page as described in the: