@Kevin As I said earlier I did both tests, and took care of every detail that caused problems, but to no avail in either case.
Alternatively I talked to the developer of my Theme (Nurui Theme), and asked for a parallel opinion, where he himself also said that there is a block for Ghost-related ads.txt, and he himself recommended that I test other names and that would work correctly.
My setup is working normally and I have several clients with Ghost, using Nginx, Varnish and CWP and without any kind of bug except curiosity about this file.
Currently I was able to reproduce the domain.com/ads.txt lock on my server, and my theme owner also had the same problem, and you say you didn’t reproduce the same problem on local tests.
I’m going to upload a test instance and do a fresh install with Ghost-CLI, so I’ll have a fourth test to complete on this issue…I’ll be back here to share other tests