1. Disconnect the community workspaces that you don't really need or rarely, if ever, participate in. You can always reconnect periodically to get caught up. 2. Leave channels that you never participate in or waste time - like joke and water cooler channels. 3. Mute channels that you rarely participate in, but don't want to hurt anyone's feelings by leaving. 4. Stay out of most conversations that aren't directly related to your work. 5. Use threads and encourage others to use threads so no one has to scroll through conversations that don't pertain to them. 6. Mark yourself as away when you need to be heads down. 7. (Maybe better) Close Slack when you need to be heads down. 8. Don't respond to channel communication immediately, unless something really requires your immediate attention. 9. Don't respond immediately to every DM, unless it's important.
Essentially, do self care and set reasonable boundaries.