Express just stops working ???

For reference the compatible browsers are : Safari, Firefox, Edge and Chrome.

I am also using Firefox for Adobe Express, but used Edge when it was not available on FF prior. The firefox availability is very new, and it's still lacking a couple of features compared to the 3 other compatible ones (and all the alternative browsers that use either FF or Chrome as a base). I will try to find out if it's part of one of the usual bug, and come back if/when I have an answer.

In Edge I see :

In Firefox, I just see:

No blockers active, same computer.  If I look in the developer options on Firefox, there are dozens of 403 errors:

Yet, if I click on one of the URLs, it loads fine.  This is on a brand new document.  I never use the software, just trying to troubleshoot for my wife!

I just tried on my machine (Firefox, Edge and Chrome) and all work as intended for me.
Is there any pop-up blocker or that kind of things on the non-working browsers?
This is what I got in Edge

and this is what I got in Firefox

Is there a particular set of action that lead to it not working?
Was the cloud symbol showing a syncing status (with a rotating aroow) instead of a static one like this one?