I managed to go through the link you provided and the according forum link (Online channel not working after upgrading UniFi Controller to 5.12.35) and I do not expect this to be the same error. With the BUG you provided the link for, OH is connected to the Unifi Controller but do not update the status of channels. In my case, the connection to the controller is disruptet because of a communication error.
The error in my case says the buffer for the answer is 2MB and the answer is to large (“Buffering capacity 2097152 exceeded”) and if I try the corresponding API call “https://:8443/api/s//stat/sta” I get an answer which is 5.6MB (“5865901”).
Is there any configuration where I can enlarge the buffer size?