On MDN Web Docs website, they have mentioned that the total specificity for the selector button:not(#mainBtn, .cta) is as follows:
| Selector | Identifiers | Classes | Elements | Total specificity
| button:not(#mainBtn, .cta) | 1 | 0 | 1 | 1-0-1
Here is the URL of the MDN Website: (https://developer.mozilla.org/en-US/docs/Learn/CSS/Building_blocks/Cascade_and_inheritance.
See the highlighted portion for the error:

I am expecting this:
| Selector | Identifiers | Classes | Elements | Total specificity
| button:not(#mainBtn, .cta) | 1(for #mainBtn) | 1(for .cta) | 1(for button) | 1-1-1
I am expecting this:

Can someone please let me know if I am right?
The MDN page you link to covers this, but not, IMO, in a particularly clear fashion. It says:
The Selectors specification describes it more precisely:
So, for
:not(#mainBtn, .cta)we take the greater of the two selectors in the list:So the greater of these is 1, 0, 0, and then we add the
buttonspecificity = 0, 0, 1And the result is 1, 0, 1.