tweak

packages/svelte/src/compiler/phases/3-transform/server/transform-server.js

@@ -908,14 +908,14 @@ function serialize_element_spread_attributes(
 		(element.type === 'RegularElement' && is_custom_element_node(element))
 			? b.false
 			: b.true;
-	const is_svg = element.metadata.svg ? b.true : b.false;
-	const is_mathml = element.metadata.mathml ? b.true : b.false;
+
+	const is_html = element.metadata.svg || element.metadata.mathml ? b.false : b.true;
+
 	/** @type {import('estree').Expression[]} */
 	const args = [
 		b.array(values),
 		lowercase_attributes,
-		is_svg,
-		is_mathml,
+		is_html,
 		b.literal(context.state.analysis.css.hash)
 	];
 

packages/svelte/src/internal/server/index.js

@@ -289,20 +289,12 @@ export function css_props(payload, is_html, props, component) {
 /**
  * @param {Record<string, unknown>[]} attrs
  * @param {boolean} lowercase_attributes
- * @param {boolean} is_svg
- * @param {boolean} is_mathml
+ * @param {boolean} is_html
  * @param {string} class_hash
  * @param {{ styles: Record<string, string> | null; classes: string }} [additional]
  * @returns {string}
  */
-export function spread_attributes(
-	attrs,
-	lowercase_attributes,
-	is_svg,
-	is_mathml,
-	class_hash,
-	additional
-) {
+export function spread_attributes(attrs, lowercase_attributes, is_html, class_hash, additional) {
 	/** @type {Record<string, unknown>} */
 	const merged_attrs = {};
 	let key;
@@ -352,7 +344,7 @@ export function spread_attributes(
 		if (lowercase_attributes) {
 			name = name.toLowerCase();
 		}
-		const is_boolean = !is_svg && !is_mathml && DOMBooleanAttributes.includes(name);
+		const is_boolean = is_html && DOMBooleanAttributes.includes(name);
 		attr_str += attr(name, merged_attrs[name], is_boolean);
 	}