I’m sorry you’re caught in the middle. I very literally can’t help you in that I’m just a user like you with absolutely zero power over what Apple or Canon may do.
There is an unfortunate reality in that users are often caught between two giants - both of whom will blame the other guy.
apple makes changes in their operating system and the burden is on developers or users of that operating system to accommodate apple’s changes. That’s how it’s always been. And, in a way, it makes sense in that they can’t accommodate every single person or company that has something on their platform.
The thing is, sometimes those using the platforms may not know every change, or may not have the skill to respond to those changes so they want apple to help them. (I’m saying this in regards to a company or developer here)
In both cases, Apple and the other big companies, if they do issue fixes, often quietly slip them in without admitting they’re fixes.
The best thing for a user to do is become adept in work arounds for certain situations.
I personally have always found air print to be minimalistic at best, often lacking controls or the finesse to really do a good job printing. My printer has been broken for quite some time but I used to use the app Print n Share when I needed better control in printing things. You may find a third party app that works better with your printer. You’d need to do some research. If Canon has a support forum there may be folks there talking about an app they use that can guide you, or you can read some reviews (change the sort from most helpful to most recent….I’ve found that ‘most helpful’ reviews are sometimes months to years old positive reviews that may not reflect the current state of an app.)
In your situation, with an older printer that worked and a newer one that does not is that there is like some incompatibility between the printer and the ipad/air print. Canon will never admit it’s their fault - if it is, neither will Apple. You could look to see if Canon has any forum or support site where other users may have fixes or work arounds, or look for a work around yourself - which could be looking for an app to bridge the gap and get your printing functionality back.
I’m sorry I don’t have a quick fix. I’ve used ipads for the better part of a decade and always have 2 ways to do things to get around random issues like this. Work arounds are faster than trying to get corporate entities to do things.
