Why does the index.nginx-debian.html magically appear in my /var/www/html/ folder?

I’ve been struggling with a strange issue affecting my droplets: after some running time, the homepage of my website would be replaced by the default, “Welcome to nginx!” screen. This repeatedly happened on a machine that was already set up and did not have any of those default nginx files.

I usually destroy the droplet and immediately rebuild it from backup (since it’s a live server, I wanted to minimize the downtime), but since I’ve seen the issue is reappearing I decided not to do it this time and investigate what happens exactly.

I’ve started with the nginx configuration files, which were identical, but then I’ve found this file “magically” appeared in my /var/www/html/ folder:

index.nginx-debian.html

Any idea why and how this might happen?

I’ve always started with a fully working version from a snapshot, then after a day or so of running fine, this file suddenly appears there and messes up my homepage. I will proceed to change the order in which the files are looked for, in the config, but this issue really bugs me at the moment.

Any idea?

Thanks!