diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 917ca860aa..d97161e470 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -519,7 +519,7 @@ jobs:
         with:
           node-version: ${{ env.CI_NODE_VERSION }}
       - name: Fetch base branch
-        run: git fetch --no-tags origin "${GITHUB_BASE_REF}" --depth=1
+        run: git fetch --no-tags origin "${GITHUB_BASE_REF}"
       - name: Validate source changes include tests
         run: node scripts/check/check-pr-test-policy.mjs --summary-file .artifacts/pr-test-policy.md
       # Anti test-masking: flag net assert removal / new assert.ok(true) in changed tests.
diff --git a/changelog.d/maintenance/ci-pr-test-policy-shallow-base.md b/changelog.d/maintenance/ci-pr-test-policy-shallow-base.md
new file mode 100644
index 0000000000..340b60a5ce
--- /dev/null
+++ b/changelog.d/maintenance/ci-pr-test-policy-shallow-base.md
@@ -0,0 +1 @@
+- CI: `pr-test-policy` fetches the base branch with full history instead of `--depth=1` — the shallow graft made `merge-base` resolve wrong for PR branches that recently merged the release, so the three-dot diff blamed the PR for OTHER merged PRs' changes (false "deleted test"/"weakened asserts" reds; observed on #7329 being blamed for #7106's files).