The ESAE architecture is being deprecated. It's not that surprising given recent changes to Microsoft's cloud infrastructure and the huge shift to remote working.
Enhanced Security Admin Environment (ESAE) architecture mainstream retirement
Retiring the red forest as a legacy security mechanism
it's detailed in the link above, but the replacement is to a Privileged Access (PA) strategy. There's a useful guide on that here
Rapidly modernize your security infrastructure
Key initiatives to rapidly secure your environment