Highlighting and allTermsRequired are hardwired in AnalyzingInfixSuggester for non-contextual lookup (via Lookup) see true, true below:
The above means the majority of the current infix suggester lookup always return highlighted results with allTermsRequired in effect. There is no way to change this despite the options and improvement of
LUCENE-6050, made to incorporate Boolean lookup clauses (MUST/SHOULD). This shortcoming has also been reported in SOLR-6648.
The suggesters (AnalyzingInfixSuggester, BlendedInfixSuggester) should provide a proper mechanism to set defaults for highlighting and "allTermsRequired", e.g. in constructors (and in Solr factories, thus configurable via solrconfig.xml).