This is not where you ask questions directly to Apple, but I think I can answer it for you.
Apple no longer supports your MacBook Air, due to its age. It's 9 years old, and though it may work fine and have plenty of storage, Catalina is as far as you can go with the osx updates. The internal architecture of your MBA can't handle the Big Sur code. We all run into this issue eventually. You either stick with whatever os you're running, and take the risks of something going wrong, or buy something new(er) that can run the newer osx updates.
Another reason to get a new(er) computer is the older they get the more likely they'll experience some sort of catastrophic failure; usually the hard drive will fail, the battery won't charge anymore, or the external ports quit working, but you never know.
I had to replace my 2018 MBA keyboard 2 weeks after I updated it to Big Sur. It worked perfectly before the update. Not sure why Big Sur screwed up the laptop keyboard, but it did. The keyboard issue happened to so many Apple laptops after updating to Big Sur, that Apple is covering the cost of replacement keyboards for those laptops that qualify under the "Service" notice.