macOS and iOS spoken content issue

I hope it's appropriate to be posting this here. If not, I apologize. I am not here to solicit tech support. I just would like to explain what's happening and possibly get some info from people that might have an idea about what's going on and if there could be any unintended side effects.

I am not sure how long it's been happening but today I was playing around with spoken content and I found that it was saying the wrong thing. It was reading 18,641,135 as Eighty million ... instead of the correct 18 million. I found that if I make it 641,135 it says that correctly. If I change to 8,641,135 it also says that correctly but if I change it to the 18,641,135 it goes back to saying 80 million.

Since I was experimenting at this time I realized it's not the usual voice I have it set to. I checked and it was on Siri (Compact Voice 1), so I set it to the preferred Siri (Voice 4) and found that it reads the number correctly.

I am just curious what would cause a sound profile to read a numerical number incorrectly and could this cause other problems anywhere or would just hearing the wrong thing be the only consequence here.

MacOS Ventura 13.1

Interestingly the same thing happens on my iPhone and listening to it can tell its a different voice that on my Mac. I went searching and found that it was set to American Voice 4 in Siri & Search but that's not the voice that's getting used. So I'm not sure where you set the voice for when you highlight and select Speak in IOS. But the same issue happens there.