Index: wp-content/themes/twentynineteen/sass/blocks/_blocks.scss
===================================================================
--- wp-content/themes/twentynineteen/sass/blocks/_blocks.scss	(revision 53503)
+++ wp-content/themes/twentynineteen/sass/blocks/_blocks.scss	(working copy)
@@ -169,7 +169,7 @@
 		.wp-block-button__link {
 			@include button-transition;
 			border: none;
-			font-size: $font__size-sm;
+			font-size: inherit;
 			@include font-family( $font__heading );
 			line-height: $font__line-height-heading;
 			box-sizing: border-box;
Index: wp-content/themes/twentynineteen/style-rtl.css
===================================================================
--- wp-content/themes/twentynineteen/style-rtl.css	(revision 53503)
+++ wp-content/themes/twentynineteen/style-rtl.css	(working copy)
@@ -5484,7 +5484,7 @@
 .entry .entry-content .wp-block-button .wp-block-button__link {
   transition: background 150ms ease-in-out;
   border: none;
-  font-size: 0.88889em;
+  font-size: inherit;
   font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Oxygen", "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif;
   line-height: 1.2;
   box-sizing: border-box;
Index: wp-content/themes/twentynineteen/style.css
===================================================================
--- wp-content/themes/twentynineteen/style.css	(revision 53503)
+++ wp-content/themes/twentynineteen/style.css	(working copy)
@@ -5496,7 +5496,7 @@
 .entry .entry-content .wp-block-button .wp-block-button__link {
   transition: background 150ms ease-in-out;
   border: none;
-  font-size: 0.88889em;
+  font-size: inherit;
   font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Oxygen", "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif;
   line-height: 1.2;
   box-sizing: border-box;