Toxicity or Deficiency?

Correct, if not insect damage, this is a deficiency of magnesium. Extra Cal/Mag should solve this.

360 ppm is too low I think. She’s probably hungry. Make sure NPK is appropriate for this stage.

The thrips are deposited on the back of the leaves, look with a magnifying glass. In hydroponics, there are no excesses; if there are too many nutrients, the roots get blocked and there's a deficiency. Your ppm is in the right range. If they aren't thrips, add a little cal-mag.

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If it is not from insects then you need cal mag.

I'm sorry to tell you that it's neither too much nor too little.. but when I zoom in on photo nr2 of the leaf, they look like thrips to me. If you want confirmation, take a magnifying glass and check the leaves for tiny black dots or very small bugs, look carefully because they're not easy to spot. I hope I'm wrong.