[giantg2]

It depends. If this is only for a month or so while the launch happens, this may be fine. If this is a pattern or ongoing, then I would say it's an issue. Even if it's durning the launch, if you need a day off and disconnect, take it. Just tell them you need the day off for whatever reason (an appointment, travel, to recharge). They should be understanding. You can even make the argument that you're only a mid-level, so your senior and tech lead should be able to support your work or contact you if absolutely necessary.

You could try suggesting an on-call schedule too. That way you don't have to be on slack during off-hours as much.