I’m pretty sure this is related to a bug that has been fixed and will be available in a nightly release later this week.
Same as this one: Modbus TCP uncontrolled polling
Confusingly, the fix is available in the current 8.0.9 nightly release, but there is a “hot fix” 8.0.9 release coming today that will not actually include it. The next nightly release that includes it will be for 8.0.10.