We are having the same issue, and the automated phone agent was worthless--didn't recognize that we were calling about this printer and wouldn't put me through to a human before hanging up on me.
Ours is the Imageclass MF733cdw. It has printed fabulously for years, but recently it began printing ghosts on the edges of any pages we print.
I'm attaching a photo of the page that printed with the fixing assembly cleaning. Already tried both "reduce ghost" settings, cleaning the ITB, reducing faint print after replacing cartridge (we only use Canon certified toner) , reduce drum streak, and drop pattern reduction mode.
The issue looks like there is loose toner powder on the rollers or there is some thing wrong with the hardware. In this situation, you can try removing all of the toner from the printer and you can wipe any exposed rollers with a damp cloth and check the inside for any loose toner powder that you can wipe up.
Once the inside has been cleaned, you can try cleaning the fixing assembly one more time to see if the issue has been resolved. If it is still there, you can try replacing your black cartridge to see if it resolves the issue.
If that does not resolve the print issue, it looks like the printer needs service. You can log into your MyCanon account to check for any available service options.