Target links not buttons.

spearhead/assets/sass/_text.scss

@@ -2,7 +2,7 @@
     border-bottom: 1px solid transparent;
     transition: all 0.1s ease;
 
-    &:hover {
+    &:hover:not(.wp-block-button__link) {
         color: var( --global--color-primary-hover );
         border-bottom: 1px solid var( --global--color-primary-hover );
     }

spearhead/style-rtl.css

@@ -136,7 +136,7 @@ Tags: one-column, flexible-header, accessibility-ready, custom-colors, custom-me
 	transition: all 0.1s ease;
 }
 
-.has-link-color a:hover, a:hover {
+.has-link-color a:hover:not(.wp-block-button__link), a:hover:not(.wp-block-button__link) {
 	color: var(--global--color-primary-hover);
 	border-bottom: 1px solid var(--global--color-primary-hover);
 }

spearhead/style.css

@@ -136,7 +136,7 @@ Tags: one-column, flexible-header, accessibility-ready, custom-colors, custom-me
 	transition: all 0.1s ease;
 }
 
-.has-link-color a:hover, a:hover {
+.has-link-color a:hover:not(.wp-block-button__link), a:hover:not(.wp-block-button__link) {
 	color: var(--global--color-primary-hover);
 	border-bottom: 1px solid var(--global--color-primary-hover);
 }