This seems to have started happening for most internet connected Canon printers starting sometime end of May.
I have a Maxify MB2020 and it started to endlessly power cycle out of nowhere. I was ready to get rid of it and by another printer since I've had the MB2020 for at least 7 years with no issues. Then I came across this forum and this solution which worked perfectly: https://community.usa.canon.com/t5/Desktop-Inkjet-Printers/MX490-power-cycling-fix-from-user-on-foru...
Basically, if your DNS setting on the printer is set to Automatic, then it's most likely trying to contact/arp your gateway and failing so it restarts and keeps on repeating the same step.
To fix this, go to your DNS settings and change it to be set Manually and then select an unused IP address on your subnet.
For example my printer ip address was 192.168.86.71 and the DNS it was trying to use is 192.168.86.1 (which is my gateway. I changed the printer's DNS to use 192.168.86.2 which is not used by any device connected on my subnet.
