nginx how to execute php scripts on "internal" uris?

I have a problem getting php scripts to execute in internal sites loaded via X-accl-Redirect.. My /etc/nginx/sites-enabled/devdb.easy-ads.com file contains:

server {
        root /srv/http/devdb.easy-ads.com/www;
        index index.html index.htm index.nginx-debian.html index.php;
        server_name devdb.easy-ads.com;
        location / {
                # First attempt to serve request as file, then
                # as directory, then fall back to displaying a 404.
                try_files $uri $uri/ =404;
        }


        # pass PHP scripts to FastCGI server
        #
        location ~ \.php$ {
                include snippets/fastcgi-php.conf;
        #
        #       # With php-fpm (or other unix sockets):
                fastcgi_pass unix:/run/php/php8.1-fpm.sock;
        #       # With php-cgi (or other tcp sockets):
        #       fastcgi_pass 127.0.0.1:9000;
        }
        error_page 404 = /index.php;
        location /phpmyadmin_internal {
                internal;
                alias /srv/http/phpmyadmin;
        }
    listen [::]:443 ssl ipv6only=on; # managed by Certbot
    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/devdb.easy-ads.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/devdb.easy-ads.com/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot

}

and in /srv/http/devdb.easy-ads.com/www/index.php i have:

<?php
header("X-Accel-Redirect: /phpmyadmin_internal/test2.txt");

and everything works great, it loads the file /srv/http/phpmyadmin/test2.txt just as expected. However when I change it to

<?php
header("X-Accel-Redirect: /phpmyadmin_internal/test.php");

it just serves a 404 error, instead of executing /srv/http/phpmyadmin/test.php .. what gives? how can i get it to execute php scripts on internal sites?

(what i THINK is happening, is that it asks php-fpm to load the literal url /phpmyadmin_internal/test.php , not properly giving it a new uri/root-dir before sending it off to php-fpm, but i don't actually know.)

first remove the alias directive for /phpmyadmin_internal, just do:

       location /phpmyadmin_internal {
                internal;
        }

then make a symlink to the target folder like

ln -s '/srv/http/phpmyadmin/' '/srv/http/devdb.easy-ads.com/www/phpmyadmin_internal'

and voila, everything works (-: