First of all most devices use Zigbee or Zwave radios, different then WiFi.
If a jammer were able to block the specific frequencies of the radios, then the devices would fall off the network.
There is no reasonable way to overcome this.
But the realities of a powerful enough signal jammer to sustain blocking all devices on a zigbee mesh or zwave or even wifi spectrum are difficult to pull off.
Proximity to the hub is the most critical element, but also the distance to each device.
Ultimately, if a jammer were deployed, it would drop the devices off the mesh, until the jammer stopped working, or the signal strength RSI, etc wasn’t strong enough to overcome the transmit radio.
Thankfully ST does have a hub disconnect notification, so you would know if the internet was cut, but there is no really good mechanism for a device falling off the network notification.
It would be easier to just cut the network connection to the house, or even power. Or just kick in the front door or break a window.
Every security system is vulnerable to many attack vectors no way to overcome this. Locks keep honest people out.