ReverseProxy rewrite 172...16:port/#1234 host.domain.com (extern)

I try to rewrite an internal url with the structure http://172.20.20.16:3777/#53584 over the ReverseProxy on host.domain.com.
Unfortunately, the proxy cuts off everything from the comment hash "#".
A rewrite to %23 ("#") does not work on the php system side.

Does anyone have any idea how "#" can be masked?

my config:

server {
listen 80;

server_name host.domain.de;
return 301 https://$server_name$request_uri;
}

server {
listen 443 ssl;

server_name host.domain.de;

root /var/www/host-certbot-webroot;

# The public and private parts of the certificate are linked here
ssl_certificate /etc/letsencrypt/live/host.domain.de-0001/fullchain.pem; # managed by Certbot
ssl_certificate_key /etc/letsencrypt/live/host.domain.de-0001/privkey.pem; # managed by Certbot


location / {
proxy_set_header Accept-Encoding "";

# WebFront http://172.20.20.16:3777/#53584
proxy_pass "http://172.20.20.16:3777/%2353584";
proxy_redirect default;

sub_filter "172.20.20.16:3777/%2353584" "host.domain.de";
sub_filter_once off;
}
}