- Set a reminder to go fuck around with your LinkedIn profile for a few minutes every couple months, so at no point are you suddenly active on it (and so, probably thinking about looking for a new job).

- If you have a job in an office with a relaxed dress code (like most devs, probably) make a point of dressing interview-nice at least a couple times a month, from the start. That way it's not notable when you happen to dress nice one day and also happen to take a slightly long lunch....

If someone would question my work ethic or similar because of my Slack status I would explain to them that this is bogus. If they insist, I would complain about them with their boss. If that all is not futile I would just find another job.