How does Nginx 1.21.0 use variables in ssl_certificate?

Solution for How does Nginx 1.21.0 use variables in ssl_certificate?
is Given Below:

Example URL:ssvwv.com

set $a ssvwv.com;
ssl_certificate /www/$a/fn.pem;

I see in the error log that the path becomes:/www//fn.pem

Correct should be:/www/ssvwv.com/fn.pem
Nginx 1.21.0 version variable is invalid?

Since version 1.15.9 Variables can be used
Using the $ssl_server_name.crt variable to the file name is invalid.
example:/www/ssvwv.com/$a.pem
error result:/www/ssvwv.com/.pem

variable example:$ssl_server_name Variable value:www.ssvwv.com
path example:/www/ssvwv.com/$ssl_server_name.pem
error result:/www/ssvwv.com/.pem
The test is invalid in the path variable.

ssl_certificate is set inside your blockserver

See an example below

server {
    listen 443;
    ssl on;
    ssl_certificate /etc/ssl/ssl-bundle.crt;
    ssl_certificate_key /path/to/your_private.key;
    root /path/to/webroot;
    server_name your_domain.com;
}
access_log /var/log/nginx/nginx.vhost.access.log;
    error_log /var/log/nginx/nginx.vhost.error.log;
    location / {
        root /var/www/;
        root  /home/www/public_html/your.domain.com/public/;
        index index.html;
    }
}