My favourite issue with Teams was that we would sometimes receieve messages from colleagues out of order, and without any notification. The UI would happily -

My favourite issue with Teams was that we would sometimes receieve messages from colleagues out of order, and without any notification. The UI would happily - and silently - insert N lines of conversation above the last line you've read. Quite often the delay could be in the minutes. We figured this out after many frustrated sessions of "but I already gave that context / sent that info". This didn't happen very often, but even just two or three shaky days in a quarter left us with a bad feeling. If you can't trust something as simple as chat delivery, it doesn't give a great feeling.