changed the default back to spaces (with "")

pylint/checkers/format.py

@@ -223,7 +223,7 @@ class FormatChecker(BaseTokenChecker, BaseRawFileChecker):
                 "type": "non_empty_string",
                 "metavar": "<string>",
                 "help": "String used as indentation unit. This is usually "
-                '"    " (4 spaces) or "\\t" (1 tab).',
+                '"    " (4 spaces) or "\\t" (1 tab).',  # noqa: RUF001
             },
         ),
         (