I’ve not read an actual answer to your question in the comments so far. If you live somewhere where WhatsApp is the dominant chat app, then you are already a data point for Meta. Unless nobody has your phone number in their contacts. If you’re concerned about a specific entry in your list of contacts, then it depends on your own point of view. You could use the same logic a above to justify sharing it. You could also decide that you don’t like that logic and you do not. So, how much worse is it? Probably inconsequential. Just to add some aluminium; when using whatsapp your phone data (brand, android version, etc) are added to big data.