diff --git a/api/config/__tests__/parsers.spec.js b/api/config/__tests__/parsers.spec.js
index 5c6953ce02..88ee977604 100644
--- a/api/config/__tests__/parsers.spec.js
+++ b/api/config/__tests__/parsers.spec.js
@@ -43,6 +43,20 @@ describe('formatConsoleMeta', () => {
     expect(meta).toBe('{"userField":"keep"}');
   });
 
+  it('drops numeric-index-like keys (splat artifacts from primitive args)', () => {
+    const meta = formatConsoleMeta({
+      level: 'warn',
+      message: 'Unhandled step:',
+      timestamp: 'ts',
+      0: 'f',
+      1: 'o',
+      2: 'o',
+      realField: 'real',
+    });
+
+    expect(meta).toBe('{"realField":"real"}');
+  });
+
   it('drops empty, null, undefined, function, and symbol values', () => {
     const meta = formatConsoleMeta({
       level: 'warn',
diff --git a/api/config/parsers.js b/api/config/parsers.js
index 056448c23d..10516a9ec4 100644
--- a/api/config/parsers.js
+++ b/api/config/parsers.js
@@ -110,6 +110,16 @@ function extractMetaObject(source) {
     if (RESERVED_LOG_KEYS.has(key) || key.startsWith('_')) {
       continue;
     }
+    /*
+     * Skip numeric-index-like keys. When a caller passes a primitive as
+     * the second argument to `logger.warn/error`, `format.splat()` can
+     * leave character-index keys ("0", "1", ...) on `info`. Those are
+     * synthetic splat artifacts, not real metadata, and would otherwise
+     * produce noisy output now that warn/error share this path.
+     */
+    if (/^\d+$/.test(key)) {
+      continue;
+    }
     const value = source[key];
     if (value === undefined || value === null || value === '') {
       continue;