Nginx losing about 50% of requests

Hi all.
We got server A that redirects requests to server B.
Server B has primitive nginx configuration like:

server {
#proxy_connect_timeout 600;
#proxy_send_timeout 600;
#proxy_read_timeout 600;
send_timeout 600;
#gzip on;
#gzip_disable "msie6";
#gzip_types text/plain application/json;

listen 80;
listen [::]:80;
listen 443 ssl http2;
listen [::]:443 ssl http2;

ssl on;
ssl_certificate /etc/nginx/ssl/somessl_com.crt;
ssl_certificate_key /etc/nginx/ssl/somessl_com.key;

server_name serverB.com;

access_log /var/log/nginx/serverB.access.log;
error_log /var/log/nginx/serverB.error.log warn;

location = /favicon.ico {
access_log off;
log_not_found off;
}

location ^~ /here-it-redirects/ {
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $http_host;
proxy_set_header X-NginX-Proxy true;
proxy_pass http://127.0.0.1:3301/;
proxy_redirect off;
}

location /.well-known/pki-validation/905AA44F6FD269FBCF9811238D715250.txt {
alias /etc/nginx/ssl/905AA44F6FD269FBCF9811238D715250.txt;
}
}

We have statistics on the server A that shows a number of redirections twice bigger than we have incoming requests at server B.
What's the issue it can be?
Thank you