The details
As reported by Search Engine Roundtable on August 25, the notice says a missed call is chargeable when it arrives within business hours and the caller waits more than 20 seconds. Where your phone system asks the caller to press a key first, the 20 seconds start after the keypress. Follow-up calls between you and the same customer can be charged if they meet Google's valid lead criteria, but only once within 15 days of the first contact. Calls after 15 days are treated as a new lead. Google also said it is adding safeguards against spam and malicious calls.
Our read
This rewards businesses that answer the phone and penalizes those that do not. The most common cause of wasted spend will be business hours that are wider than the hours someone actually answers. Check those first. If you cannot staff the phone reliably, a call answering service will usually cost less than the leads you would otherwise pay for and lose.