I had the impression it means all WhatsApp business accounts, no matter if they use the Facebook backend or not (because for a WhatsApp business account you nee

I had the impression it means all WhatsApp business accounts, no matter if they use the Facebook backend or not (because for a WhatsApp business account you need to use the WhatsApp business app, which is the one providing the service and possibly the Facebook backend itself). But I couldn't find any confirmation. There is a WhatsApp business API that is from Facebook, but apparently you don't necessarily need to use it.