Hi there,
Lately, I have seen this issue from the Browser I use (MS Edge Version 119.0.2151.44 (Official build) (64-bit) and Firefox Version 119.0.1 (64-bit)) where I cannot access the flows I created under "My flows" link, nor the Environments on the top of the page. Occasionally, I will be able to see everything; the flows and environments that I created in Firefox but in MS Edge doesn't show anything. The Page looks as this:
This is in MS Edge:

This is in Firefox:

I got confirmation from our IT department that they have also cleared the required URLs from their firewalls.
I am unable to guess what's going wrong here but, if there are any URLs that were missed to clear from the firewall, how can know that URL? so that I can forward it to our Group IT for clearance.