Vagrant/windows using hyper-v fails; could not detect virtualbox

I apologize in advance if this is a FAQ, but I’ve searched all over.
Running vagrant 2.2.18 on windows 10 Pro 21H1
Hyper-v is properly installed
Attempting to start any box with --provider hyperv comes back with

Bringing machine 'default' up with 'hyperv' provider...
Vagrant could not detect VirtualBox! Make sure VirtualBox is properly installed.
Vagrant uses the `VBoxManage` binary that ships with VirtualBox, and requires
this to be available on the PATH. If VirtualBox is installed, please find the
`VBoxManage` binary and add it to the PATH environmental variable.

This is a clean install of vagrant; virtualbox has never been installed on this machine.

When running with -debug, it seems to start out trying to use hyperv just fine:

Bringing machine 'default' up with 'hyperv' provider...
 INFO batch_action: Enabling parallelization by default.
 INFO batch_action: Disabling parallelization because provider doesn't support it: hyperv
 INFO batch_action: Batch action will parallelize: false
 INFO batch_action: Starting action: #<Vagrant::Machine:0x000001c92faa73d8> up {:destroy_on_error=>true, :install_provider=>false, :parallel=>true, :provision_ignore_sentinel=>false, :provision_types=>nil, :provider=>"hyperv"}
 INFO machine: Calling action: up on provider Hyper-V (new)

but then inexplicably switches to virtualbox:

DEBUG host: Trying: windows
 INFO host: Detected: windows!
 INFO runner: Running action: machine_action_up #<Vagrant::Action::Builder:0x000001c92e67a978>
DEBUG base: Windows, checking for VBoxManage on PATH first
 INFO base: VBoxManage path: VBoxManage
 INFO environment: Released process lock: machine-action-ec6d8a5f578e755545ed2d26104591a7
 INFO environment: Running hook: environment_unload
 INFO runner: Running action: environment_unload #<Vagrant::Action::Builder:0x000001c92f78f9c0>
ERROR vagrant: Vagrant experienced an error! Details:

Any help greatly appreciated.

Hi. Answered your question in your GitHub issue as well but wanted to leave a note here for completeness. The cause of the error was from the vagrant-disksize plugin. Removing the plugin will resolve the error.