We have escalated the matter to Ecobee, who have released firmware to address the issue.
Ecobee has released a new firmware version 22.214.171.124 for their Ecobee 4 devices. If you have Ecobee 4, then please ensure you are running this firmware at the minimum to mitigate the issue.
Ecobee has released firmware version 3.70.992 for their Ecobee 3 devices that addresses the issue with channel changes. If you have Ecobee 3, then please ensure you are running this firmware to mitigate the issue.
Ecobee has confirmed that firmware 126.96.36.1991 for Ecobee 3 does not contain the channel change fix, but are working on a newer firmware that will address the issue.