Index: src/wp-content/themes/twentytwentyone/assets/sass/05-blocks/image/_style.scss
===================================================================
--- src/wp-content/themes/twentytwentyone/assets/sass/05-blocks/image/_style.scss	(revision 54423)
+++ src/wp-content/themes/twentytwentyone/assets/sass/05-blocks/image/_style.scss	(working copy)
@@ -11,11 +11,21 @@
 	}
 
 	.alignright {
+
+		/*rtl:ignore*/
 		margin-left: var(--global--spacing-horizontal);
+
+		/*rtl:ignore*/
+		margin-right: 0;
 	}
 
 	.alignleft {
+
+		/*rtl:ignore*/
 		margin-right: var(--global--spacing-horizontal);
+
+		/*rtl:ignore*/
+		margin-left: 0;
 	}
 
 	a:focus img {
@@ -57,6 +67,7 @@
 			@include media(mobile-only) {
 				margin-left: 0;
 				margin-right: 0;
+				float: none;
 			}
 		}
 	}