Just an hour ago Apple has released updates for all the firmwares of its devices. It is strange, since for iPhone, iPad and Apple Watch it has only taken a week to release the first update. For Macs it is already something more normal, since the previous version of macOS Catalina went to mid july.
A few days ago a problem with the graphics card came to light that some users of the 27-inch iMac. This update fixes it, also fixing some minor bugs. So even if you don't have said iMac, it is better to update, just in case.
Apple just released the latest version of its firmware for Macs an hour ago, macOS Catalina 10.15.7. An update that incorporates bug fixes for some users, but perhaps most importantly, it solves a graphical problem that manifests itself in some 27-inch iMac from this year.
The graphical problem came to light around August 31, with different user complaints appearing on social media and in Apple's support forums. The information that appeared in this regard was not very clear, and the problem did not seem to manifest itself only during intense workloads, but even when the affected iMac was idle.
Not all users complained about the bug, as the problems were mainly focused on the iMac with a processor 9GHz 3,6-core Core i10, 32GB memory, 5700GB AMD Radeon Pro 16 XT graphics. A very localized bug in a very specific configuration.
The update also includes some fixes issued in an interim supplemental update for Catalina, released for select machines in early September. So if Apple has released this update, even if it's the last one before Big Sur macOSLet's be good users and proceed to download it.