Need help configuring SAML behind Nginx reverse-proxy

Your software
My Mautic version is: 4.4.3
My PHP version is: 8.0
My Database type and version is: mysql 8.0

Current setup uses nginx + php-fmp to serve Mautic, nginx config is based on this gist: Mautic Nginx Configuration · GitHub

The problem in all SAML-related paths (/saml/metadata.xml, /s/saml/login) are being redirected to main entry point /s/dashboard or /s/login in case anonymous access.

Could anyone please help crafting proper nginx config to support SAML?