If Apple follows tradition versioning methodology Big Sur is going to be a
Major release, v11.x.x.
Prior OS versions have been 10.x.x. For instance;
From Wikipedia - the macOS was previously known as Mac OS X and later OS X and 10.0 "Kodiak" was released in 9/2000.
Now after 20 years of updates:
So, Apple has been layering code over the base 10.0 core for 20 years. The specter of "spaghetti coding" comes to mind as it looks like Apple may be following the Windows method of development. Features change and are added/subtracted without request or warning. The product (Catalina) may be suffering under the weight of years of unstructured and uncoordinated development (my assumption).
All that being said, in theory Big Sur v11. will be remaking the OS much deeper in its core than previously. This change is good and bad. The good is Apple may need to go deeper into the core to address issues that have crept into v10. The bad is what are going to be the "unintended consequences" of opening that box.
Because Big Sur will be a major release, the beta testing will be critical. Early adopters beware.
For now, Catalina will most likely retain many of the issues mentioned in this "short" thread. For some, there is the option to downshift to Mojave or High Sierra, but only if Catalina is intolerable. I've decided to remain on High Sierra for my 2017 iMac, it just works fine for now.