Disable Rich tracebacks by default (#6576)

redbot/core/_cli.py

@@ -314,6 +314,19 @@ def parse_cli_flags(args):
         default=None,
         help="Forcefully disables the Rich logging handlers.",
     )
+    # DEP-WARN: use argparse.BooleanOptionalAction when we drop support for Python 3.8
+    parser.add_argument(
+        "--rich-tracebacks",
+        action="store_true",
+        default=False,
+        help="Format the Python exception tracebacks using Rich (with syntax highlighting)."
+        " *May* be useful to increase traceback readability during development.",
+    )
+    parser.add_argument(
+        "--no-rich-tracebacks",
+        action="store_false",
+        dest="rich_tracebacks",
+    )
     parser.add_argument(
         "--rich-traceback-extra-lines",
         type=non_negative_int,