Big Sur

we're not sure as the technology may be too in-advanced for the new update unfortunately

The macOS Big Sur Preview page on Apple's website includes a list of compatible hardware:

• MacBook: 2015 and later

• MacBook Air: 2013 and later

• MacBook Pro: Late 2013 and later

• Mac mini: 2014 and later

• iMac: 2014 and later

• iMac Pro: 2017 and later

• Mac Pro: 2013 and later

I have a Late 2012 iMac that works perfectly fine, with good CPU, RAM, etc..., and I can not understand why is not being supported by Big Sur.

I am pretty sad, I would upgrade to a new iMac but I can not at this moment. :(

for iMac - you need 2014 - and for those that think that even 2014 is broken by Big Sur:

I'm sharing an iMac Late 2014 (the oldest computer that is said to work with Big Sur)

It was very slow so we fully wiped the computer and installed a fresh copy of Big Sur, and it was still very slow, laggy etc.

We left the computer on doing nothing for 2 days and now it's fully fast as it was before - there are 2 days of background update processes that the mac doesn't tell you about...