I get the following message when I try to edit my app (I was editing it successfully yesterday):
The webpage at https://us.create.powerapps.com/api/start?action=edit&source=portal&app-id=%2fproviders%2fMicrosoft.... might be temporarily down or it may have moved permanently to a new web address.
I spoke too soon. It now will sometimes start to open in edit mode, but when it asks me to confirm my sign-in authorization, it tells me I can't get to the wesbite anymore. So I'm back to square one.