That's a customizable setting in Flow. You can have it launch your default browser or open it internally. There's also the pros and cons of auth/cookie isolati

That's a customizable setting in Flow. You can have it launch your default browser or open it internally. There's also the pros and cons of auth/cookie isolation. You'll need to log in to Slack again. But if you use it for, say, Facebook it will work like the isolation feature in FF.