Strapi API Rest V 3.6.8 how to search posts by title?

I have installed version 3.6.8 of Strapi

In the docs for v3.xhttps://strapi.gitee.io/documentation/v3.x/content-api/parameters.html#filter

Filters are used as a suffix of a field name:

• No suffix or eq: Equals
• ne: Not equals
• lt: Less than
• gt: Greater than
• lte: Less than or equal to
• gte: Greater than or equal to
• in: Included in an array of values
• nin: Isn't included in an array of values
• contains: Contains
• ncontains: Doesn't contain
• containss: Contains case sensitive
• ncontainss: Doesn't contain case sensitive
• null: Is null/Is not null

And I can see those examples

GET /restaurants?_where[price_gte]=3

GET /restaurants?id_in=3&id_in=6&id_in=8

etc..

So I tried

/posts?_where[title_contains]=foo/posts?title_contains=foo

And I also tried the "new way" in V4

/posts?filters[title][contains]=foo

But all of this attempts return all the post, exactly the same than just doing

/posts?

Any idea how to filter by post title and/or post body?