The CoAP protocol is the next big thing for DDoS attacks CoAP DDoS attacks have already been detected in the wild, some clocking at 320Gbps December 5, 2018 https://www.zdnet.com/article/the-coap-protocol-is-the-next-big-thing-for-ddos-attacks/
Attackers Use CoAP for DDoS Amplification February 4, 2019 https://www.securityweek.com/attackers-use-coap-ddos-amplification
IoT stuff makes great reflectors. Just like botnets. Good plain-vanilla residential and business IPs.
IoT devices using CoAP increasingly used in DDoS attacks March 8, 2019 https://www.helpnetsecurity.com/2019/03/08/iot-coap-ddos-weapon/ The State of DDoS Weapons (PDF - 6.39 MB): https://www.a10networks.com/sites/default/files/A10-EB-14115-EN.pdf