I suffered through this nasty surprise yesterday. But after my morning coffee, I found someone who had solved it.
This guy solved it.
He wrote the fix for GCP, but it's not a cloud vendor specific issue, it's an oversight with the Apache configuration.
The TLDR is that you have to get this line:
RequestHeader set X-Forwarded-Proto "https"
Into this file:
And you're good.
Restart Ghost and you'll be able to connect to Stripe and stuff.