If Nhost's Postgres says type icu does not exist when using pg_search tokenizers, two things must both be true: the database must be on a recent image (17.9 or later, where the maintainer fixed the packaging) and pg_search must actually be installed with CREATE EXTENSION in that database. Check SELECT * FROM pg_extension for pg_search before assuming the tokenizer is broken. The same applies to other extensions Nhost ships but does not enable by default.

Context: GitHub issue nhost/nhost#4012 (closed, 5 comments): on Nhost's managed Postgres, using the pg_search icu tokenizer failed with type icu does not exist. The maintainer fixed the underlying image packaging in the next release and showed it working on the 17.9 image, but the reporter's error persisted until they actually installed the extension: the tokenizers are only available after CREATE EXTENSION pg_search. After installing it, the reporter confirmed the icu tokenizer worked.