diff --git a/types/google-publisher-tag/google-publisher-tag-tests.ts b/types/google-publisher-tag/google-publisher-tag-tests.ts
index 0b7021e8b879eb..fc4f3ebd53b712 100644
--- a/types/google-publisher-tag/google-publisher-tag-tests.ts
+++ b/types/google-publisher-tag/google-publisher-tag-tests.ts
@@ -1,5 +1,5 @@
-// Tests for Google Publisher Tag 1.20260420
-// Synced from: https://github.com/googleads/google-publisher-tag-types/commit/fec849a853dfba65b7059ba9c2f6a30bbcfa4add
+// Tests for Google Publisher Tag 1.20260518
+// Synced from: https://github.com/googleads/google-publisher-tag-types/commit/26b00c99eb377e0e93b1510a795f2e647d91d8e5
 
 // Test for googletag.cmd
 function test_googletag_cmd() {
diff --git a/types/google-publisher-tag/index.d.ts b/types/google-publisher-tag/index.d.ts
index 0b93356851c994..225f8937c13905 100644
--- a/types/google-publisher-tag/index.d.ts
+++ b/types/google-publisher-tag/index.d.ts
@@ -2794,7 +2794,12 @@ declare namespace googletag {
         /**
          * Supported interstitial ad triggers.
          */
-        type InterstitialTrigger = "unhideWindow" | "navBar" | "inactivity" | "backward" | "endOfArticle";
+        type InterstitialTrigger =
+            | "unhideWindow"
+            | "navBar"
+            | "inactivity"
+            | "endOfArticle"
+            | /** @deprecated */ "backward";
 
         /**
          * Settings to configure video ad related settings.
diff --git a/types/google-publisher-tag/package.json b/types/google-publisher-tag/package.json
index 635bbea05c307d..b3307bd42c23e0 100644
--- a/types/google-publisher-tag/package.json
+++ b/types/google-publisher-tag/package.json
@@ -1,7 +1,7 @@
 {
     "private": true,
     "name": "@types/google-publisher-tag",
-    "version": "1.20260420.9999",
+    "version": "1.20260518.9999",
     "nonNpm": "conflict",
     "nonNpmDescription": "Google Publisher Tag",
     "projects": [