Except thousands of people and CDCK hosting would also likely be affected and they are not. It’s much more likely that you deleted or added a character to a line in your app.yml.
You can do stuff like this:
grep -i S3 /var/discourse/containers/*
docker exec -it app bash -c 'grep s3 /var/www/discourse/config/discourse.conf
And if you configured s3 in settings instead of with ENV variables, then you can have a look at Configure an S3 compatible object storage provider for uploads to see what those look like.