<type name="MagentoCatalogBlockProductAbstractProduct">
    <plugin name="Amasty_Stockstatus::Addstatus" type="AmastyStockstatusPluginProductStatus" />
</type>

namespace AmastyStockstatusPluginProduct;

class Status
{
    CODE

    public function afterToHtml(
    MagentoCatalogBlockProductAbstractProduct $subject,
    $result
    ) {
        CODE
    }
}

<type name="AmastyStockstatusPluginProductStatus">
    <plugin name="Amasty_Stockstatus::Addstatus" type="VendorExtensionNamePluginProductStatus" sortOrder="1" />
</type>

namespace VendorExtensionNamePluginProduct;

class Status extends AmastyStockstatusPluginProductStatus
{
    public function afterToHtml(
        MagentoCatalogBlockProductAbstractProduct $subject,
        $result
    ) {
        NEW CODE
    }
}

<preference for="AmastyStockstatusPluginProductStatus" type="VendorExtensionNamePluginProductStatus"/>

<type name="MagentoCatalogBlockProductAbstractProduct">
    <plugin name="Amasty_Stockstatus::Addstatus" disabled="true" />
</type>

<type name="MagentoCatalogBlockProductAbstractProduct">

<plugin name="Addstatus" type="VendorExtensionNamePluginProductStatus" sortOrder="1" />

<plugin name="Vendor_ExtensionName::Addstatus" type="VendorExtensionNamePluginProductStatus" sortOrder="1" />