magento 2.4 canUseCheckout not working anymore

A while ago I successfully hid the checkmo payment method from frontend only by setting the variable canUseCheckout to false via preference:

-- V/M/etc/di.xml
    <preference for="MagentoOfflinePaymentsModelCheckmo" type="VMModelCheckmo" />

-- V/M/Model/Checkmo.php
class Checkmo extends MagentoOfflinePaymentsModelCheckmo {
    protected $_canUseInternal = true;
    protected $_canUseCheckout = false;
}

This has always worked fine until recently when we have upgraded our magento from 244 version to 246 and we also switched from cloud to community.

I don’t know if it was the upgrade or the migration from cloud to community, but this preference is not working anymore. More than that, the preference gets ignored completely:

class Checkmo extends MagentoOfflinePaymentsModelCheckmo
{
    protected $_canUseInternal = true;
    protected $_canUseCheckout = false;

    public function canUseCheckout() // this method is never called, only the  original method from magento Checkmo class. 
    {
        //return $this->_canUseCheckout;
        return false;
    }

Is there a way to have this working again?