only in patch2:
unchanged:
--- a/core/modules/system/config/schema/system.schema.yml
+++ b/core/modules/system/config/schema/system.schema.yml
@@ -353,6 +353,17 @@ block.settings.system_menu_block:*:
       type: integer
       label: 'Maximum number of levels'
 
+block.settings.system_page_tabs_block:
+  type: block_settings
+  label: 'Tabs block'
+  mapping:
+    primary_tasks:
+      type: integer
+      label: 'Whether primary tabs is shown'
+    secondary_tasks:
+      type: integer
+      label: 'Whether secondary tabs is shown'
+
 condition.plugin.request_path:
   type: condition.plugin
   mapping: