The change was made to comply with how the Home Assistant team suggests button events should be handled.
Z2M’s documentation has warned (for a long time) to avoid using the legacy method to detect button events.
@teleoltre
The option you enabled is likely to be eliminated eventually. You should consider adapting your automations to use either a State Trigger with your device’s associated event entities or the MQTT Device Trigger (assuming all desired button events are supported).
Here’s a good explanation for how to use a device’s event entities.