Based on the clarifications that were posted by Wizards:

https://magic.wizards.com/en/news/announcements/commander-brackets-beta-update-april-22-2025

I think that the default bracket level should probably be 2. The bracket 1 (Exhibition) should be for concept decks, like an all white-bordered deck with a card starting with each letter of the alphabet. I recommend making the default level 2, and additionally letting people assign their own brackets to deck, based on the builder's intent. I think that the work that you've built for the auto-evaluation should move to a recommendation.

I wanted to jump in and concur. Thank you so much for building the tool, but agree on both points that it should be a suggestion and should start at 2.