That means, that somewhere (sometimes) a configuration gets used with PHP 8.5 that tries to load opcache.so manually (zend_extension=opcache.so). It probably isn't the default PHP configuration, otherwise you'd would have seen a lot more of the same error in the syslog. Although that also depends on how many domains your have running with PHP 8.5. My guess would be that there might be some domain specific configuration that tries to load the opcache module/extension.