I have this N.sibuyanensis and the first pitcher it produce some black deform part. The second is not that much. It is place under 50% shade with high humidity with sphag moss and perlite as mediaSo i wonder is this has anything to do with humidiy, temperature etc? Any suggestion?

The pitcher before fully grown. Some blackening is shown

first pitcher produced. Note the lid is deformed

The second pitcher. Only the 'wing' part looks burn.