How to cut nginx url

I am using nginx to proxy requests to three services. I need to cut request url and proxy to services with changed url.
Here example:
example.com/blabla/admin/dashboard/... -> proxy to
localhost:8080/admin/dashboard/...
I want to do it for safety reasons, of course I can make subdomain (blablabla.example.com/admin/dashboard), but I think url is safer
than subdomain.

I am tried this configuration, But it just proxy with original url:

upstream web1 {  
    server site1:8080;  
}  
  
upstream web3 {  
    server site3:8080;  
}  
  
upstream web2 {  
    server site2:8080;  
}  
  
server {  
    listen       80;  
    listen  [::]:80;  
    # server_name  localhost;  

    location /balaboba {  
        proxy_pass http://web1$uri;  
    }  
  
    location /catsruletheworld {  
        proxy_pass http://web2$uri;  
    }  
  
    location /lolkek {  
        proxy_pass http://web3$uri;  
    }  
}  

$uri is the original URL, so you are explicitly sending it in your proxy_pass statements.

proxy_pass within a prefix location can automatically achieve what you are trying to do. Simply use a trailing / on both the location and proxy_pass statements to substitute the prefix for /. See proxy_pass documentation.

For example:

location /foo/ {
    proxy_pass http://service/;
}

In the above, the URL http://example.com/foo/bar will be passed to http://service/bar

This only works if the service is well behaved and does not generate absolute links that break out of the imposed prefix. In which case the subdomain approach may be safer after all.