Issue #2315189 by herom: Fixed 2 schema element types mistyped as sequence.

core/modules/comment/config/schema/comment.schema.yml

@@ -36,7 +36,7 @@ action.configuration.comment_unpublish_by_keyword_action:
       type: sequence
       label: 'Keywords'
       sequence:
-        - type: sequence
+        - type: string
           label: 'Keyword'
 
 action.configuration.comment_unpublish_action:

core/modules/node/config/schema/node.schema.yml

@@ -124,7 +124,7 @@ action.configuration.node_unpublish_by_keyword_action:
       type: sequence
       label: 'Keywords'
       sequence:
-        - type: sequence
+        - type: string
           label: 'Keyword'
 
 block.settings.node_syndicate_block: