This is not the case. The browser extension (as well as the Desktop app and Web Vault) uses Full-Text Search, but the mobile apps only have Basic Search available. Therefore, results can be different.
That is the silliest decision I’ve heard. Everyone knows that you want a consistent experience across mediums/platforms. I mean take a que from Apple and how they are making changes to macOS and iOS to have a more common and consistent experience.
It makes no sense that mobile search and web/browser/extension search is different. That’s just bad design.
I submitted a feature request to change this.
In case anyone comes across this thread and wants to upvote my feature request.
It is most likely a technical limitation that is preventing Full-Text Search from working in the mobile apps. To make the search experience consistent across all devices, Bitwarden would probably have to downgrade the non-mobile search functionality so that it is restricted to Basic Search only.
Feel free to have a look at (or contribute to) the codebase on GitHub. It’s likely a limitation of the library that is used for searching. The non-mobile apps use the Lunr.js library, but the mobile apps are mostly implemented in C#.
I would say it’s more like “we’re not going to waste our time reinventing the wheel by rolling our own custom search engine, so we’ll just import suitable search utilities from libraries that are available for the mobile and non-mobile platforms, respectively.”