Regarding https://wordpress.org/plugins/varnish-http-purge 5.1.3 Users with Editor role who are not administrator should be able to use the button "Purge Cache (This Page)".

purge_single_page_non_admin.patch

diff -ru plugin.orig/varnish-http-purge.php plugin.modified/varnish-http-purge.php
--- plugin.orig/varnish-http-purge.php	2023-05-27 10:07:28.893638677 +0200
+++ plugin.modified/varnish-http-purge.php	2023-05-27 10:07:37.241770054 +0200
@@ -410,19 +410,6 @@
 				);
 			}
 
-			// If we're on a front end page and the current user can edit published posts, then they can do this.
-			if ( ! is_admin() && get_post() !== false && current_user_can( 'edit_published_posts' ) ) {
-				$page_url = esc_url( home_url( $wp->request ) );
-				$args[]   = array(
-					'parent' => 'purge-varnish-cache',
-					'id'     => 'purge-varnish-cache-this',
-					'title'  => __( 'Purge Cache (This Page)', 'varnish-http-purge' ),
-					'href'   => wp_nonce_url( add_query_arg( 'vhp_flush_do', $page_url . '/' ), 'vhp-flush-do' ),
-					'meta'   => array(
-						'title' => __( 'Purge Cache (This Page)', 'varnish-http-purge' ),
-					),
-				);
-			}
 
 			// If Devmode is in the config, don't allow it to be disabled.
 			if ( ! VHP_DEVMODE ) {
@@ -452,6 +439,19 @@
 				);
 			}
 		}
+			// If we're on a front end page and the current user can edit published posts, then they can do this.
+			if ( ! is_admin() && get_post() !== false && current_user_can( 'edit_published_posts' ) ) {
+				$page_url = esc_url( home_url( $wp->request ) );
+				$args[]   = array(
+					'parent' => 'purge-varnish-cache',
+					'id'     => 'purge-varnish-cache-this',
+					'title'  => __( 'Purge Cache (This Page)', 'varnish-http-purge' ),
+					'href'   => wp_nonce_url( add_query_arg( 'vhp_flush_do', $page_url . '/' ), 'vhp-flush-do' ),
+					'meta'   => array(
+						'title' => __( 'Purge Cache (This Page)', 'varnish-http-purge' ),
+					),
+				);
+			}
 
 		if ( $can_purge ) {
 			foreach ( $args as $arg ) {