don't over-encode, do try to decode, fixes #85521

src/vs/workbench/api/common/extHostTypeConverters.ts

@@ -289,16 +289,23 @@ export namespace MarkdownString {
 		if (!data) {
 			return part;
 		}
+		let changed = false;
 		data = cloneAndChange(data, value => {
 			if (URI.isUri(value)) {
 				const key = `__uri_${Math.random().toString(16).slice(2, 8)}`;
 				bucket[key] = value;
+				changed = true;
 				return key;
 			} else {
 				return undefined;
 			}
 		});
-		return encodeURIComponent(JSON.stringify(data));
+
+		if (!changed) {
+			return part;
+		}
+
+		return JSON.stringify(data);
 	}
 
 	export function to(value: htmlContent.IMarkdownString): vscode.MarkdownString {