If you want to be sure the developers see it, you need to submit it as an “issues” ticket.
Having said that, have you tried setting up a Chan-SIP connection using the same credentials to see if Chan-SIP works? If the problem goes away on Chan-SIP and is reproducible on PJ-SIP, then you have a smoking gun that you include on the ticket.
It’s possible that it might be a problem at the remote end and is simply a coincidence. Obviously, since several people are seeing it, it could be something in the PJ-SIP stack, but if it was, we’d be hearing a LOT of noise about this and it doesn’t seem like a widespread problem.