FIX Don't destroy attribute proxies if root proxy is leaked and GC'd (#1870)

docs/project/changelog.md

@@ -36,6 +36,11 @@ substitutions:
   `PyProxy` (as introduced by {pr}`1636`) before destroying the root `PyProxy`.
   {pr}`1854`
 
+- {{Fix}} Borrowed attribute `PyProxy`s are no longer destroyed when the root
+  `PyProxy` is garbage collected (because it was leaked). Doing so has no
+  benefit to nonleaky code and turns some leaky code into broken code (see
+  {issue}`1855` for an example). {pr}`1870`
+
 ### pyodide-build
 
 - {{API}} By default only a minimal set of packages is built. To build all

src/core/pyproxy.js

@@ -31,7 +31,6 @@ Module.isPyProxy = isPyProxy;
 
 if (globalThis.FinalizationRegistry) {
   Module.finalizationRegistry = new FinalizationRegistry(([ptr, cache]) => {
-    pyproxy_decref_cache(cache);
     try {
       Module._Py_DecRef(ptr);
     } catch (e) {