config.js - editing/changing values is not reliable
I added "allowGravatar": "false", in the config.js. "allowFreeUrl" is set to true. I restarted the app after editing values. 4 of 5 restarts doesn't change anything. One time it was possible to see no connection to cdn.libravatar.org the other 4 there was a connection.
It was never possible to use a freeurl for my instance. Free means - the user can choose the url for the document (instead of an auto generated BAQdUImATHWGqLiaopmTlg strings).
Is this the same on your instances?
See https://docs.hedgedoc.org/configuration/#users-and-privileges for more options.
I am not sure how hedgedoc handles the config file delivery, but an I can't see how an app restart would load an old config file.
Can you check if this is some caching issue? It seems you can fetch https://hedgedoc.example.com/config for your instance to verify the settings you've mentioned.