Sitecore Content Search indexes data field by name and type. When you introduce a new module with a new data template you may create a new field with a name that already exists on another template but has a different type. In this case, you will get indexing errors and some data may not be indexed.
However, Sitecore will not warn you about this clash. It will only break during indexing, which you may not spot straight away.
- Always prefix template field names with template name to address the field name and type clash during indexing (Solr, Azure Search).
-- Populate user-friendly field title.
- Monitor your Sitecore logs for the indexing errors.