--- a/scripts/generate-hg-s3-bundles
+++ b/scripts/generate-hg-s3-bundles
@@ -31,17 +31,17 @@ PUSH_REPO = '/var/hg/version-control-too
 CREATES = [
     ('gzip', ['bundle', '-a', '-t', 'gzip-v1'], {}),
     ('gzip-v2', ['bundle', '-a', '-t', 'gzip-v2'], {'gd': True}),
     ('bzip2', ['bundle', '-a', '-t', 'bzip2-v1'], {}),
     # ``zstd`` uses default compression settings and is reasonably fast.
     # ``zstd-max`` uses the highest available compression settings and is
     # absurdly slow. But it produces significantly smaller bundles.
     ('zstd', ['bundle', '-a', '-t', 'zstd-v2'], {'all': True}),
-    ('zstd-max', ['--config', 'experimental.bundlecomplevel=22',
+    ('zstd-max', ['--config', 'experimental.bundlecomplevel=21',
                   'bundle', '-a', '-t', 'zstd-v2'], {'all': True}),
     ('stream-legacy', ['streambundle'], {}),
     ('packed1', ['streambundle', '--type', 's1'], {}),
     ('packed1-gd', ['streambundle', '--type', 's1'], {'gd': True}),
 ]
 
 BUNDLECLONE_ORDER = [
     ('gzip', 'compression=gzip'),