By default, elasticsearch is used only for fulltext search (when searching for some specific text) and for some computationally intensive filters (exclude tag, the message added by the user, the message added on date and time).
If you want to enable the use of elasticsearch for all searches, you can do it by adding setting name='force_es' and value='Y' to table qu_g_settings.
The risk of using elasticsearch for all searches is that if the data in elasticsearch index is not up to date with the source data in MySQL database, the results may not be 100% the same as the search in the database would return. This may be caused by delay up to a minute in updating the elasticsearch index, which is done by a background task executed by queue.php cron job.