The missing authorization allows any authenticated user to escalate his or any other team members privileges to any role, including the owner role. He's also able to kick every other member out of the team, including admins and owners.
This allows the attacker to access the Terminal feature and execute remote commands.

PoC

App\Livewire\Team\Member::makeReadonly();
App\Livewire\Team\Member::makeAdmin();
App\Livewire\Team\Member::makeOwner();
App\Livewire\Team\Member::remove();