This request is very similar to one existing one, but it has been closed due to inactivity and comments are no longer possible.
Use case or problem
Sometimes I don’t know which of my vaults contains the note that I am searching for, which means manually searching in multiple Vaults. This also allows you to find similar notes across vaults that should better be deduplicated.
Proposed solution
Obsidian could simply search in parallel or in sequence over all open Vaults and display the combined results.