Clawing starts on new growth. My plants get fed a high N diet compared to many growers and while darker green is just fine the clawing is not ok. Heat stress can also do it but based on how your leaves look I would say it's an N excess. Back off the feed and watch the new growth to make sure there is improvement. The leaves that are clawed now won't recover.
Here are pictures of my 4 Corners crop:
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In the first picture you will see the plant in full, the lights are level with the top of the plant, so only the very top is going to have that eagle claw look. The second picture is of the top most bud site of the first picture. You will see how the leaves are curving downwards from the base to the tips and on the sides of each blade of the leaf. If you look at the first picture again you will see that all the rest of the leafs on the plant are fine and that the top most of the plant is level with the light which coincidentally according to you and DabonDabs would say I started hitting with too high a concentration of nutes causing eagle clawing which is not what happened.
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The third picture is of a plant that is getting hit on all four sides, YES 4 SIDES, of vertical 1000W SHPS lighting and is of the same crop as the above pics. The leaves having light coming from all directions just start eagle clawing from almost the bottom most fan leaf to the top of the plant, but you can see in the top right corner of the picture in the background other plants only getting hit by 1 angle of lighting and have flat leaves....and yes my entire hydro system is interconnected so they get the same nutes and these are all 4 Corner plants. So if they are getting the same concentration of nutes and one 4 Corners plant has massive eagle clawing, but you see another that looks like it has none....that should maybe tell you that vertical lighting, especially from multiple lights at multiple angles WILL cause the leaves to curl downwards which looks like eagle clawing. As you guys said, eagle clawing will only occur on new growth and not affect the fan leaves already fully developed......well if the plant in the third pic has leaves eagle clawing towards the bottom of the plant to the top, and the one in the first pic only has it at the very top where it is level with the light, then there is no way it can be N toxicity because it would impact all the plants in the setup at about the same height when the N toxicity would start.
Oh and btw, I never refuted the fact that my 501st pic, which was at the tail end of the grow, was showing a toxicity from the burning at the tips of the leaves....it was just not an N toxicity. Was hitting too high with the sensi bloom trying to push for more yield when the hairs were changing colors. And the burning of the tips show well before any eagle clawing from N toxicity unless maybe you have a strain that is super sensitive to N from what I have been told about sensi bloom.