Hello,
I recently deployed Mattermost using Docker and set up an Nginx reverse proxy following the instructions provided in the official Mattermost documentation (version 7.8.6) found here: Mattermost Docker Installation Guide.
Is there a way to change the favicon for docker deployment
I think you have multiple options here.
First you could try to overwrite the directory /mattermost/client/images/favicon in the container; just map it to a custom directory on your host using the volumes option in the docker-compose.yml file: