I feel like I need to mention this in case some eyes see it that need to hear it. If you're running global teams and you have a side of that team that has to show up at the ass-crack of dawn every morning while you get to show up at 4PM with the entire context of a full work day behind you - ROTATE THE TIMES or ASK the engineers on both ends of the spectrum how they feel about it and be understanding if some of them don't want to show up at 8am anymore. Not to mention it puts us into a super weird conversation where we're half asleep and trying to sound like we know what's going on to someone grilling us with full cognition.

Also, async is one thing. Respecting your peoples time is another thing. Slack, etc can show you what time it is in that employees time zone. How do you feel when the first thing you do is open Slack while sipping coffee and eating your bagel and your boss has 10 messages to you from 6am-9am your time?

Probably not the best start to your day. Let people log in, socialize, be humans and colleagues for a little bit before you hammer them, especially now when work is the only real human interaction some people are getting.