I don't think the bracket calculation for Commander decks should include cards in the sideboard, since sideboards aren't really part of the game. (I use the "Sideboard" group as a Maybeboard and the "Scratchpad" as a record of cards that were previously in the deck but now removed.)

Regardless of use, I agree, especially since technically Commander decks aren't allowed to have a sideboard.

Didn't realize they were used in the calculation! Thank you for pointing that out.