How to Reset the Print System. Your networked (wired/wireless) Canon TR8520 is supported by Apple's AirPrint technology that allows you to print without Canon printer drivers. AirPrint does not address scanning or faxing functionality. If Canon has current, Catalina, 64-bit compatible scanner drivers for this device, then install it. If not available, then the paid, non-subscription, 64-bit VueScan can solve your scanning needs for this device, again without any Canon software or drivers necessary. Between AirPrint and VueScan — you can be entirely independent of Canon software.
I have used VueScan Professional since 2010 on a very old Canon scanner without paying VueScan update/upgrade fees. I am not affiliated with VueScan, nor do I receive any benefit from the vendor by mentioning their product here.