It is counter-intuitive, all the more so when notifications accumulate and customers are waiting for an explanation. But as long as the facts are not confirmed, it is better to resist the temptation of the hot message. A point of situation published too quickly can mislead, or lock yourself in an untenable promise.
The good tempo is that of a first readable, factual message, and directly centered on what customers need to know: what is happening, which is concerned, what the company puts in place to solve the problem, and above all, when you will speak.
This framing is often more important than the content itself. Even if the technical response takes time, being proactive on communication shows that the situation is taken seriously.
You also have to pay attention to the tone. It is neither a question of reassuring at all costs, nor of dramatizing the facts, but of remaining sober, clear and assumed. Avoid vague or alarmist formulas as “major breakdown”, “critical incident”, or conversely “small bug”, which leave too much room for interpretation. Prefer a simple, descriptive, action -oriented vocabulary, and make no promise that you would not be able to hold a few hours later.