I have a 2014 macpro and a 2021 macAir. I'm trying to use my air to download Big Sur or even Catalina into a usb so I can factory reset my 2014 pro (acting glitchy, saying "connection not secure" on certain websites and more). I tried downloading the new new OS to a USB and failed so I went ahead and just factory reset the 2014 pressing command, option, R so that supposedly I could install the "latest" possible OS, yet I ended up with Mavriks.... And again some websites say "your connection is not secure" type message and don't work at all... EDIT: I finally got my new mac to save a copy of Big Sur into a USB, but when I went to factory reset the mac it still shows mavriks as the only option to install. If you think you can help me please email me at listadecraig123 at gmail and maybe we can get on a call and I can send you mula through Venmo.