For a few days now, Google’s Gboard has also seemed to be making suitable suggestions for answers directly in WhatsApp. Previously, these smart suggestions were only available for notifications. Irregularly, the Gboard can now also read the content of the messages with open chats and makes suggestions.
Very rare at the moment, but it happens occasionally on my Pixel 6 Pro with the latest Gboard app. This is what it looks like when Gboard offers an appropriate answer: