Based on my knowledge of the pytest codebase and the issue description, I can provide the patch. The issue is in the `_pytest/assertion/util.py` file where the sequence comparison generates the "Right contains more items, first extra item: X" message. For byte strings, this shows the integer value (ASCII ordinal) rather than something more meaningful.

The fix should skip the "contains more items" messaging for bytes objects, as suggested in the hint. Here's the patch:

--- a/src/_pytest/assertion/util.py
+++ b/src/_pytest/assertion/util.py
@@ -258,11 +258,13 @@ def _compare_eq_sequence(
     explanation: List[str] = []
     len_left = len(left)
     len_right = len(right)
     for i in range(min(len_left, len_right)):
         if left[i] != right[i]:
             explanation += [
                 f"At index {i} diff: {left[i]!r} != {right[i]!r}"
             ]
             break
     len_diff = len_right - len_left
-    if len_diff > 0:
+    if len_diff > 0 and not isinstance(left, bytes):
         explanation.append(f"Right contains {len_diff} more item{'s' if len_diff > 1 else ''}, first extra item: {right[len_left]!r}")
-    elif len_diff < 0:
+    elif len_diff < 0 and not isinstance(right, bytes):
         explanation.append(f"Left contains {-len_diff} more item{'s' if len_diff < -1 else ''}, first extra item: {left[len_right]!r}")
     return explanation