Fix optional chaining as computed key (#17486)

changelog_unreleased/javascript/17486.md

@@ -0,0 +1,20 @@
+#### Fix optional chaining as computed key (#17486 by @fisker)
+
+<!-- prettier-ignore -->
+```jsx
+// Input
+const a = { [y?.z]() {} };
+class A { [y?.z]() {} };
+
+// Prettier stable
+const a = { [y?.z]?() {} };
+class A {
+  [y?.z]?() {}
+}
+
+// Prettier main
+const a = { [y?.z]() {} };
+class A {
+  [y?.z]() {}
+}
+```