Unexpected end of input at vendor.js

I’m running Sonarr behind Nginx Reverse proxy setup using the following config:

server {
        listen 443 ssl;

        ssl_certificate /etc/letsencrypt/live/sonarr.mydomain.xy/fullchain.pem;
        ssl_certificate_key /etc/letsencrypt/live/sonarr.mydomain.xy/privkey.pem;

        error_log       /var/log/nginx/sonarr_error.log;

        server_name sonarr.mydomain.xy;

        location / {
                proxy_set_header   Host $proxy_host;
                proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header   X-Forwarded-Host $host;
                proxy_set_header   X-Forwarded-Proto $scheme;
                proxy_set_header   Upgrade $http_upgrade;
                proxy_set_header   Connection $http_connection;
                proxy_redirect     off;
                proxy_http_version 1.1;
                proxy_pass http://localhost:8989;
                auth_basic "Restricted";
                auth_basic_user_file /var/lib/sonarr/.htpasswd;

Accessing it results in:

Using the console to debug into vendors.js it seems that the file is not being fully transmitted. It seems to be suddenly ending:


Now the strange thing is sometimes it works and the Webpage is accessible and fully functioning but then it’s not.

Neither Nginx nor Sonarr logs don’t really show anything interesting. Any ideas?

Sonarr version (exact version): (just updated today)
Nginx version: 1.24.0
OS: Ubuntu 22.04.3