diff --git a/src/github/pr-actions.ts b/src/github/pr-actions.ts
index 7917733727..9545654b21 100644
--- a/src/github/pr-actions.ts
+++ b/src/github/pr-actions.ts
@@ -132,7 +132,12 @@ export async function dismissLatestBotApproval(env: Env, installationId: number,
     const { owner, repo } = splitRepo(repoFullName);
     return await withInstallationTokenRetry(env, installationId, async (token) => {
       const octokit = makeInstallationOctokit(env, token, "live", githubRateLimitAdmissionKeyForInstallation(installationId));
-      const botLogin = `${env.GITHUB_APP_SLUG}[bot]`;
+      // Compared case-INSENSITIVELY, like every other bot-login check in this subsystem
+      // (isLoopOverBotComment in comments.ts:104, normalizeGitHubSlug/isBotActor in self-authored.ts). GitHub's
+      // canonical casing for the login need not match however GITHUB_APP_SLUG happens to be configured, and a
+      // case-sensitive === would degrade to a silent no-op: no match, no error, a stale bot approval simply
+      // never dismissed (#6614).
+      const botLogin = `${env.GITHUB_APP_SLUG}[bot]`.toLowerCase();
       // Reviews are returned oldest-first; the LAST matching entry across ALL pages is the bot's most recent
       // APPROVE. Stopping at page 1 would find (or miss) the wrong review on a PR with >100 total reviews.
       let latestApprovalId: number | undefined;
@@ -140,7 +145,7 @@ export async function dismissLatestBotApproval(env: Env, installationId: number,
         const response = await octokit.request("GET /repos/{owner}/{repo}/pulls/{pull_number}/reviews", { owner, repo, pull_number: pullNumber, per_page: REVIEW_PAGE_SIZE, page });
         const batch = response.data as Array<{ id: number; state?: string; user?: { login?: string | null } | null }>;
         for (const review of batch) {
-          if (review.user?.login === botLogin && review.state === "APPROVED") latestApprovalId = review.id;
+          if (review.user?.login?.toLowerCase() === botLogin && review.state === "APPROVED") latestApprovalId = review.id;
         }
         if (batch.length < REVIEW_PAGE_SIZE) break;
       }
diff --git a/test/unit/github-pr-actions.test.ts b/test/unit/github-pr-actions.test.ts
index 3e3293c145..b8340270e1 100644
--- a/test/unit/github-pr-actions.test.ts
+++ b/test/unit/github-pr-actions.test.ts
@@ -567,6 +567,51 @@ describe("GitHub PR action primitives (#778)", () => {
     expect(calls[0]?.body).toMatchObject({ message: "stale approval retracted", event: "DISMISS" });
   });
 
+  it("dismisses the bot's approve review when GitHub returns a different login casing than GITHUB_APP_SLUG (#6614)", async () => {
+    // The regression: `Gittensory[bot]` vs the default GITHUB_APP_SLUG of `gittensory` matched nothing under
+    // the old case-sensitive ===, so this returned { dismissed: false } — a SILENT no-op, no error, leaving a
+    // stale bot approval standing. The human reviewer whose login differs only in case must still be ignored.
+    const calls: Array<{ url: string; body: Record<string, unknown> }> = [];
+    vi.stubGlobal("fetch", async (input: RequestInfo | URL, init?: RequestInit) => {
+      const url = input.toString();
+      const method = init?.method ?? "GET";
+      if (url.includes("/access_tokens")) return Response.json({ token: "t" });
+      if (url.includes("/pulls/11/reviews") && !url.includes("/dismissals") && method === "GET") {
+        return Response.json([
+          { id: 1, state: "APPROVED", user: { login: "Human-Reviewer" } },
+          { id: 2, state: "APPROVED", user: { login: "Gittensory[bot]" } }, // an EARLIER bot approve, mixed case
+          { id: 3, state: "CHANGES_REQUESTED", user: { login: "GITTENSORY[BOT]" } },
+          { id: 4, state: "APPROVED", user: { login: "GitTensory[Bot]" } }, // the LATEST bot approve — this one
+        ]);
+      }
+      if (url.includes("/pulls/11/reviews/4/dismissals") && method === "PUT") {
+        calls.push({ url, body: init?.body ? JSON.parse(String(init.body)) : {} });
+        return Response.json({ id: 4, state: "DISMISSED" });
+      }
+      return new Response("unexpected", { status: 500 });
+    });
+    const result = await dismissLatestBotApproval(envWithKey(), 123, "owner/repo", 11, "stale approval retracted");
+    expect(result).toEqual({ dismissed: true });
+    expect(calls).toHaveLength(1); // the mixed-case human's approve (id 1) was never dismissed
+  });
+
+  it("still ignores a review whose author is missing a login entirely (#6614)", async () => {
+    // The optional-chain's nullish side: `review.user?.login?.toLowerCase()` must not throw on a null author
+    // (a ghosted/deleted account) and must not match the bot.
+    vi.stubGlobal("fetch", async (input: RequestInfo | URL) => {
+      const url = input.toString();
+      if (url.includes("/access_tokens")) return Response.json({ token: "t" });
+      if (url.includes("/pulls/12/reviews")) {
+        return Response.json([
+          { id: 1, state: "APPROVED", user: null },
+          { id: 2, state: "APPROVED", user: { login: null } },
+        ]);
+      }
+      return new Response("unexpected", { status: 500 });
+    });
+    await expect(dismissLatestBotApproval(envWithKey(), 123, "owner/repo", 12, "retract")).resolves.toEqual({ dismissed: false });
+  });
+
   it("is a no-op when the bot never approved this PR", async () => {
     vi.stubGlobal("fetch", async (input: RequestInfo | URL) => {
       const url = input.toString();