Tip: If your USB printer is not detected, remove ipp-usb package.

[/RaspberryPi]

Took me a few days to get my HP USB printer detected by the raspberry pi 64-bit official image on RPi 4, neither cups admin interface nor lpinfo -v was mentioning any device on USB, although dmesg clearly shows it is connected and recognized as a USB device, I also tried blacklisting usblp but it didn't help, the only clue was that running /usr/lib/cups/backend/usb shows the line DEBUG: Failed to detach "usblp" module, while usblp is not even loaded, so it hinted that there's some usb conflict.
finally I found a tip online that there is a conflict between ipp-usb and regular USB access and by removing ipp-usb, everything just worked normally.

submitted by /u/ageek
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