Either pH or root issue ..?
As plants recently had a growth spurt the temp in tent increased from 28 to 33, does this happen with plant growth? Nothing else changed.
Hey bro. Are you checking your runoff for ph and tds. Something is out of whack. Are you feeding by label directions? If so your going overboard on nutes. I'm not sure which diary your pics are from. If you can check your runoff that will tell the story. Luck and Cheers friend
*tried uploading a follow up picture but doesn’t appear we are able?
The leaf is not hidden.
It’s kind of a gold colour.
And appears to be starting on a different plant in the same tent. That leaf is a bit hidden from light.