This is an idea for the mattermost desktop client but is probably applicable to other clients.
It would be nice to provide the option for a user to disable or freeze animated items in the interface.
There are various places where other users can put animated elements in mattermost, in the content, in a room description, in the reactions through animated emojis, and even in the user status again with animated emojis. This can be distracting for users that want to have the mattermost client open on a second screen for example. I think this is an accessibility feature and would be important for people with attention difficulties.