Flow will notify you if there is an error in the syntax of your Flow. It does NOT send an email that a credentials issue is preventing it from running at all.
Example: I had a Flow monitoring my Twitter feed and sending certain # to a SharePoint list. I changed my Twitter password forgot to update Flow. No message, no nothing. The Flow entries just stopped. Today I went into Flow to find that I had "Connection issues" with O365. Not sure why, but I hit the fix button and now it's OK. Great, but there was no notification that the connection had broken in the first place.
So now let's imagine this was a business process in a global company like mine. I'm in US Central. If Flow goes down during APAC business hours, then what happens? They just sit and wait for dawn in the US? How is that acceptable?
Again, my biggest issue here is that this risk is NOT presented to users by Microsoft.