Not sure what’s going on

Need more info in order to properly diagnose. See here for what info to include: https://www.mrgrowit.com/forum/grow-community/read-me-first

What light you use and what distance is it from the Canopy. And do you have a heater in there? is the damage just the top of the plant or where is the damage at?

Looks like heat stress or light burn

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More pictures would be beneficial as well. Is this the only plant affected?