This is a WhatsApp issue. Version 2.2502.3.0 was released in Jan 20th and had this bug. I rolled back to 2.2447.5.0 from Dec 6th and there's no echo back down to the caller. WhatsApp latest release 2.2504.2.0 released on Feb 3rd still has this bug. I've tried contacting WhatsApp support but can't get a human response, just the auto generated AI answers which hasn't been of any use.
Hope this helps someone.