I recently encountered a bug in one of our services at my job at Osmos. Our service is written in Rust and connects to GCP PubSub via its gRPC interface.
We were running into errors in our logs like this:
Error, message length too large: found 5360866 bytes, the limit is: 4194304 bytes
The service in question had been running for over 2 years without seeing this issue before, and the message size limits shown are smaller than the PubSub message size cap of 10MB.