Issue Summary

You can use CQL in advanced search or using content REST API.

While results and CQL works with rest API (example https://your-domain.atlassian.net/wiki/rest/api/content/search?cql=space=TEST)
When performing searches in the Advanced's search in UI, it does not respect the fields and operators, returning all results with a given word.

Steps to Reproduce

1. Go to Confluence advanced search
2. Use the CQL space = TEST or space = "TEST" or even something more specific like text ~ "\"hello dolly\""
3. Use the url search/API to compare results

Expected Results

Same results from the URL/API are displayed in the Advanced search UI and results are from the specified CQL search. E.g: it would return anything related to the space TEST or with the text specified

Actual Results

It brings any results with the word TEST (not only related to the space/spacekey TEST), same for the specified text, it will bring any results for content containing the words in the text.
The URL changes when you add the CQL to the search, it adds the "text" to search for any field <URL site>/wiki/search?text=<CQL_entered>
Where when you apply the filter from the UI, it changes to:
https://<urlsite>.atlassian.net/wiki/search?spaces=TEST
And there is no "text" after the /search?, added.

Workaround

Use the URL/API method or the filters in the UI.