DarkArc I wonder if search prioritization options could be encrypted with the login password (kind of like a password vault). The client would then decrypt the "settings vault" and pass along the settings to the server.
Certain Kagi settings—such as custom bangs, opening links in a new tab, interface language, theme, font size, and other appearance settings—could theoretically be implemented entirely on the client side. The browser extension can apply those settings when Privacy Pass is turned on without revealing them to the server.
However, the ranking adjustments (raise or lower domains) and other server side settings could be stored in open source projects, maintained as community efforts on platforms like GitHub, GitLab, or SourceHut. Using unpopular ranking settings would always reduce your anonymity compared to using the default rankings. Though publicly publishing customizations would at least give you plausible deniability about whether Tor searches from one day were made by the same person as Tor searches from another day, even in the case of backdoored Kagi servers.
A "settings vault" concept could be useful if you can have multiple such vaults per paid Kagi account, and when you apply good OpSec to use a vault for only one "burner identity". If somebody is this concerned about their anonymity, they might prefer to sync and back up the settings manually instead of letting Kagi store an encrypted blob.