.ebextensions config file instructions ignored

I want to upload files from my website, but nginx by default has a pretty low limit for request size, so I want to update the configuration file using an ebextension. I created a .ebextensions/nginx.config file at the root of my project with this inside:

files:
  /etc/nginx/conf.d/elasticbeanstalk/client_max_body_size.conf:
    mode: "000644"
    owner: root
    group: root
    content: |
      client_max_body_size 20M;

Then I ran eb deploy

$ eb deploy BMFT-DEV
Creating application version archive "app-fc4ae-240415_185719968838".
Uploading: [##################################################] 100% Done...
2024-04-15 16:57:27    INFO    Environment update is starting.      
2024-04-15 16:57:32    INFO    Deploying new version to instance(s).
2024-04-15 16:58:40    INFO    Instance deployment completed successfully.
2024-04-15 16:58:46    INFO    New application version was deployed to running EC2 instances.
2024-04-15 16:58:46    INFO    Environment update completed successfully.

But when I checked if the file was created on the EC2 instance, it wasn't.

# ls /etc/nginx/conf.d/elasticbeanstalk/ -all
total 8
drwxr-xr-x 2 root root  53 Apr 15 16:58 .
drwxr-xr-x 3 root root  60 Apr 15 16:58 ..
-rw-r--r-- 1 root root 397 Apr 15 16:58 00_application.conf
-rw-r--r-- 1 root root 215 Apr 15 16:58 healthd.conf

I checked the eb-engine.log file and found nothing related to my extension. It's like it was completely ignored. I don't understand what I did wrong here.

Thanks in advance.