Whatsapp can be easily not used, especially if you altogether leave the service. Only people that care will call or SMS.
The groups are unfortunate, but try to call the group admin from time to time to see if they like being ‘polled’ about any news:)
Last part was tongue in cheek. I am part of a group with a burner phone whatsapp number + tchncs matrix bridge which throws the encryption out of the window.
But honestly what I found after leaving whatsapp was just that nothing was lost and I can still have friends;)
Edit: according to WhatsApp Users by Country 2023 there are 9+ Million users in my country (Romania) and this is like “all people with a phone that can install an app”, yet I am still good.