.... that's something I don't get, and it happens over and over again.
A bug is being introduced. That happens.
The bug gets reported.
The doesn't get forwarded to the developers within 24 hours - that's ok, this game is no critical part of our lives.
The bug doesn't get fixed within the next 24 hours - that's ok, too, the game is still playable.
But: Why don't you simply withdraw the conflicting commit (I sincerely hope you use some kind of version control software) until someone finds the time to fix the buggy code?
Especially when it's something that doesn't conflict with anything else.
Message notification over web socket doesn't work yet? Send the old style notifications and keep the listener until the new one works. That's code which doesn't affect other parts of the game, it's like having two letter boxes for a couple living together, and once they get married and share the same name, they can dismount the one bearing the other name
And why, for heaven's sake, do you have to roll out the bug to the live servers more than two weeks after the report?
What's going wrong here? Can you give an explanation which isn't a malfunctioning reporting chain, incapacity or ignorance?