update for Catalina for keyboard a2450

So this really perplexed me and I finally found the answer. On the latest magic keyboard A2450 none of the top row F1 - F12 work with Catalina... only Big Sur and later. I know you can put sound in the menu bar and that's great, works. But for brightness this is what I found. Go to System preferences, keyboard, shortcuts, display. there are two items there using other keys for the display that don't work on this keyboard. Highlight these and change the keys to F1 and F2 respectively. Makes my Catalina 10.15.7 work with this keyboard. I did the latest security update and not sure if that made it work or not but its now working fine. Wonder if Apple knows about this.? Love Catalina don't want to upgrade, but did need new keyboard.

That is not an option on this A2450 keyboard. However when I pair my A1644 it is an option. The only thing it says with new A2450 keyboard is a box that says Show keyboard and emoji viewers in menu bar. the use F1 F2 etc keys as standard keys is not there, so Im thinking because my machine is 10.15.7 and the compatibility of this new keyboard is 11.3. I did find a way to make the brightness work on F1 and F2 so Im happy. Maybe some day I will get enough courage to upgrade but not now. Thanks for your help.

I just bought new A2450 keyboard, the latest one available. None of the F top row work. everything else works. because it is not compatible for Catalina (which I have). it works with Big Sur which I don't really want to upgrade to. was hoping there was a way to make all the F1 through F12 work without an update. Sound, and brightness is only interest.

My Mac is a 21.5 inch 2017. I bought it in December of 2020. It's not very old at all. The problem is I don't have upgrade Big Sur 11.3 and don't want to stop using Catalina 10.15.7. So now the most important keys work so Im happy.

Thanks for all the input. Im so used to Catalina Im not sure about Big Sur and once you've put it on your Mac it can't be undone. I will just deal with the keyboard for awhile.