Magento 2.4 Plugin afterGetPrice() – issues with Full Page Cache

I am overriding the frontend price by using the MagentoCatalogModelProduct plugin like so:

Sulman/Mymodule/etc/frontend/di.xml

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="MagentoCatalogModelProduct">
        <plugin name="sulman-product-model-frontend" type="SulmanMymodulePluginProductPlugin" sortOrder="1" />
    </type>
</config>

SulmanMymodulePluginProductPlugin.php:

<?php

namespace SulmanMymodulePlugin;

class ProductPlugin
{

    public function afterGetPrice(MagentoCatalogModelProduct $subject, $result)
    {
        return '123.45'; // just testing
    }
}
?>

This is working correctly but when FPC is enabled the prices do not update. (e.g. if I load the page, then change the return price to 789.99 then refresh frontend the price stays at 123.45 – If i then clear cache 789.99 then shows).

How can I get around the cache?

Thanks

Magento 2.4.1