It can help to alert the user of something that happened, in a part of the screen that is not currently on focus, and that is not important enough to disrupt the user by moving VoiceOver’s focus to a different place.
It can be useful to announce certain messages like errors or long running tasks that have finished (i.e. a download that finished) or with custom notifications and snack bars.
You may also find interesting...
With the attribute accessibilitySpeechPunctuation, you can ask VoiceOver to speak any punctuation marks in your attributed accessibility label, if that is what you want. Good for code snippets?
"We have one job, and that's to make our apps work. And if you are not implementing accessibility features, you are forgetting about making it work for a lot of people" @NovallSwift Couldn't have said it better! https://x.com/novallswift/status/1328387659744505856
You should convey important information in multiple modes, not just color. If you are still required to do so, at the very least you should complement that info with other modes, like symbols, if the user requested differentiation without color.
