While we wait for the release of macOS Big Sur 11, we still have Macs on macOS Catalina to take care of. And Apple today released an OS update for these computers.
macOS Catalina 10.15.7 is now available. Here are the release notes:
Resolves an issue where macOS does not automatically connect to Wi-Fi networks
Resolves an issue that could prevent files from syncing via iCloud Drive
Resolves a graphics issue that may occur on iMac (Retina 5K, 27-inch, 2020) with Radeon Pro 5700 XT
Apple also has a support document that describes the security updates. The security updates also apply to Macs running macOS High Sierra 1
Before installing the update, back up your Mac. To install the update, click on the Apple menu and select About this Mac. Then click Software update button that appears in the Overview tab. The update is 2.84GB and requires your Mac to restart.