July 12, 2022—KB5015807 (OS Builds 19042.1826, 19043.1826, and 19044.1826)

MattiasB3 Microsoft have come back to us and said they are looking into the cause for now they have provided a couple of possible work arounds I have used the NeutralResources via Intune Policies rather than GPO but the result should be the same.  My users can now access the few URL's we need to work via IE computability mode.  I dismissed the option of disabling Edge MDAG completely however we did test that on a test device and it also fixed the issue so seems to be something in the MDAG isolation policies causing the issue post patch.

Add the sites in the IE Mode list as trusted in the Network Isolation policy. On the gpedit the path to the polices -> Computer Configuration\Administrative Templates\Network\Network Isolation.

1. For intRAnet sites, you’ll need to add their IP addresses & the corresponding Network Domains to EnterpriseIPRanges (Network Isolation\Private network ranges for apps) & EnterpriseNetworkDomainNames (Intune only) policy
2. For intERnet sites, you’ll need to add their domains to either EnterpriseCloudResources (Network Isolation\Enterprise resource domains hosted in the cloud) or NeutralResources (Network Isolation\Domains categorized as both work and personal) policy

OR

                  Stop targeting Edge MDAG policies to those machines

Hope this helps you.