Update

syntax/modules/substitutions.vim

@@ -0,0 +1,9 @@
+if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'nginx') == -1
+  
+" Substitutions Module <https://www.nginx.com/resources/wiki/modules/substitutions/>
+" A filter module which can do both regular expression and fixed string substitutions on response bodies.
+syn keyword ngxDirectiveThirdParty subs_filter
+syn keyword ngxDirectiveThirdParty subs_filter_types
+
+
+endif