diff --git a/wagtail/admin/views/generic/models.py b/wagtail/admin/views/generic/models.py
index 542a48ce62..4cc7618c25 100644
--- a/wagtail/admin/views/generic/models.py
+++ b/wagtail/admin/views/generic/models.py
@@ -1164,7 +1164,6 @@ class RevisionsCompareView(WagtailAdminTemplateMixin, TemplateView):
     history_label = gettext_lazy("History")
     page_title = gettext_lazy("Compare")
     template_name = "wagtailadmin/generic/revisions/compare.html"
-    _show_breadcrumbs = True
     model = None
 
     def get_breadcrumbs_items(self):
diff --git a/wagtail/contrib/search_promotions/views/settings.py b/wagtail/contrib/search_promotions/views/settings.py
index 7d8d80c914..b35d978135 100644
--- a/wagtail/contrib/search_promotions/views/settings.py
+++ b/wagtail/contrib/search_promotions/views/settings.py
@@ -87,7 +87,6 @@ class SearchPromotionCreateEditMixin:
     edit_url_name = "wagtailsearchpromotions:edit"
     form_class = forms.QueryForm
     header_icon = "pick"
-    _show_breadcrumbs = True
     page_subtitle = gettext_lazy("Promoted search result")
 
     def get_success_message(self, instance=None):