Element API - Filter on a value from a multi value field
When you wrap your term in asterisks, e.g. *news*, the generated SQL for this query parameter uses a LIKE operator for the ANDWHERE condition is uses (see Element Queries).

Make sure that the values for the Select field don’t overlap (sportnews and news both matching *news*).

'bannerPageCategories' =&gt; "*{$target}*"