I don't think nested virtualisation ever worked when Hyper-V/WSL2 was enabled on the Windows 10 20H2 host.

Starting with version 15.5.5
With Hyper-V enabled on the Windows 10 host, the virtual machine monitor (VMM) will be using the Windows Hypervisor APIs (can see this in the vmware.log as Monitor Mode: ULM). This is what allowed Hyper-V on the host to co-exist with running VMware Workstation VMs. But nested VMs capability (the "Virtualized Intel VT-x/EPT o AMD-V/RVI is checked in the VM processor settings) will show the error message that you see.

Without Hyper-V enabled on the Window 10 host, the VMM is the regular ring 0 Intel VT-x (in vmware.log Monitor Mode: CPL0) and nested virtualisation works.

I guess you need to make a choice either

(1) have WSL2 on the host and lose nested VM capability in Workstation VMs, or
(2) disable WSL2/Hyper-V on the host and have nested virtualisation on VMs (which also means you can have WSL2, Docker, etc inside the VMs).

Probably best to go with option (2) especially if you want different VMs requiring nested virtualisation capability (e.g. WSL2, Docker or plain vanilla VM running inside a VM).