WSL2 hinders VirtualBox to work

I installed VirtualBox Version 6.1.18 r142142 (Qt5.6.2) onto my Windows 10 box. It worked seamlessly.

Then I installed WSL2 and some guest Linuxes onto it. For that, I installed the October 2020 latest version of Windows 10.

Now, when I try to run a VirtualBox VM, I get

Failed to open/create the internal network   
'HostInterfaceNetworking-VirtualBox Host-Only Ethernet Adapter' 
(VERR_INTNET_FLT_IF_NOT_FOUND).
Failed to attach the network LUN (VERR_INTNET_FLT_IF_NOT_FOUND).

Result Code: 
E_FAIL (0x80004005)
Component: 
ConsoleWrap
Interface: 
IConsole {872da645-4a9b-1727-bee2-5585105b9eed}

I have found a long discussion of this conflict that contains

Just installed VB 6.1.18 and to my surprise it's now working fine alongside with WSL 2.

As I stated above, I have VirtualBox 6.1.18 but it does not work.

What should I do?

It's not the same conflict at all. The two parties are now fighting over an entirely different thing – this time the error message is about VirtualBox being unable to attach to a network interface, not about being unable to attach to the hypervisor.

Run ncpa.cpl and find the "VirtualBox Host-Only Network" interface in there. Right-click it, choose "Properties" and make sure the "VirtualBox NDIS6 Bridged Networking Driver" is present.

If that doesn't help, try reinstalling VirtualBox, as the installer will re-create the Host-Only Network interfaces from scratch every time.

(Previously VirtualBox couldn't use the entire virtualization feature, as there can be only one hypervisor per machine. Recent VirtualBox versions support running on top of the Windows hypervisor instead of the one shipped with VirtualBox.)