Version 11.0.1, build 20B29
Officially, this drops support for Ivy Bridge systems with Intel HD4000 graphics to raise the minimum requirements to Haswell graphics. Yet, as per all beta versions, Big Sur 11.0.1 still provides all the drivers required to support HD4000 graphics so it can be installed and run on such platforms with full graphics acceleration.
nVidia Kepler graphics remain fully supported. A notable exception to these specifications appears to apply to the iMac14,1/2/3 (Haswell models with Iris Pro 5200 or Kepler GT7x5M graphics) that all appear officially unsupported.
Also released at the same time:
High Sierra 10.13.6 Security Update 2020-006 (build 17G14042), which should be the last one, High Sierra reaching end of support. Mojave 10.14.6 Security Update 2020-006 (build 18G6042).