Updating another column if a column was dirty using observer results in stack overflow

public function saveProfile(): void
    {
        $this->user->update(
            $this->profileForm->getState(),
        );
    }

public function saveProfile(): void
    {
        $this->user->update(
            $this->profileForm->getState(),
        );
    }

public function updated(User $user)
    {
        if ($user->isDirty('username')) {
            $user->update([
                'username_changed_at' => now()
            ]);
        }
    }

public function updated(User $user)
    {
        if ($user->isDirty('username')) {
            $user->update([
                'username_changed_at' => now()
            ]);
        }
    }