Why Does Nginx Stop Responding to Server Names After a While?

I'm currently running GitLab and an Apache server for Nextcloud on Ubuntu. Everything seems to work fine for a bit, but then it just randomly stops functioning as expected. My GitLab domain directs traffic correctly to GitLab and my Nextcloud domain directs to Apache (which runs on port 8090). However, at some point, it suddenly starts redirecting all the traffic to the Apache server, ignoring both the `server_name` and the `default_server` parameters that I've set up for Nginx.

Here's the configuration I'm using that has worked sporadically. I've noticed that it usually starts functioning again after I rename the configuration file to something else, restart Nginx, and then rename it back to its original name followed by another restart. Here's the relevant part of my Nginx config:

server {
listen 80;
listen [::]:80;
server_name example.com;
return 301 https://$server_name$request_uri;
}
server {
listen 443 ssl;
listen [::]:443 ssl;
ssl_certificate [redacted];
ssl_certificate_key [redacted];
ssl_protocols TLSv1.2 TLSv1.3;
ssl_prefer_server_ciphers on;
ssl_ciphers [redacted];
ssl_session_cache shared:SSL:10m;
ssl_session_timeout 10m;
access_log /var/log/nginx/cloud-access.log;
error_log /var/log/nginx/cloud-error.log error;
root /var/www/nextcloud;
server_name example.com;
client_max_body_size 0;
location / {
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header Host $host;
proxy_pass http://127.0.0.1:8090;
}
}