https://unicode-org.atlassian.net/browse/ICU-22132
https://bugzilla.mozilla.org/show_bug.cgi?id=1790071
https://hg.mozilla.org/releases/mozilla-esr115/raw-file/tip/intl/icu-patches/bug-1790071-ICU-22132-standardize-vtzone-output.diff

Index: source/i18n/vtzone.cpp
--- source/i18n/vtzone.cpp.orig
+++ source/i18n/vtzone.cpp
@@ -1735,14 +1735,17 @@ VTimeZone::write(VTZWriter& writer, UErrorCode& status
             }
         }
     } else {
-        UnicodeString icutzprop;
-        UVector customProps(nullptr, uhash_compareUnicodeString, status);
+        UVector customProps(uprv_deleteUObject, uhash_compareUnicodeString, status);
         if (olsonzid.length() > 0 && icutzver.length() > 0) {
-            icutzprop.append(olsonzid);
-            icutzprop.append(u'[');
-            icutzprop.append(icutzver);
-            icutzprop.append(u']');
-            customProps.addElement(&icutzprop, status);
+            LocalPointer<UnicodeString> icutzprop(new UnicodeString(ICU_TZINFO_PROP), status);
+            if (U_FAILURE(status)) {
+                return;
+            }
+            icutzprop->append(olsonzid);
+            icutzprop->append(u'[');
+            icutzprop->append(icutzver);
+            icutzprop->append(u']');
+            customProps.adoptElement(icutzprop.orphan(), status);
         }
         writeZone(writer, *tz, &customProps, status);
     }