If your instance is using the V1 classic experience and the homePageSearchBarMode parameter does not set the search context as expected, you must set isUnifiedSearchExperienceEnabled to false. This disables the unified search and allows the homePageSearchBarMode to control the search bar mode, enabling natural language search as desired.
If isUnifiedSearchExperienceEnabled is true, the unified search experience takes precedence, and the search bar defaults to object search, regardless of the homePageSearchBarMode setting.
Can you check :
https://developers.thoughtspot.com/docs/full-app-customize
V1/v2/v3