The thrips i experience outdoors leave bronze patches where they feed. They are kind of shiny splotchy patches. My eyes aren't great and the pic doesn't show too much distinct damage. Crumpled a bit.
Don’t intend to sound like a smart ass but our crystal ball is in the shop.... we need more info.
What”s your soil mix or grow media? What size container? How long has it been in that container? Which nutes? Are you using cal-mag? What’s your water source? Do you set ph? What value are you setting ph? How often do you water? Is plant in veg or flower?
As said, it is very hard to diagnose a problem by looking at detached leaves. It looks like a magnesium deficiency at first glance, but without seeing it occurring on the plant and where on the plant it is, that is only a guess.
There may not be anything wrong other than this common deficiency. It happens when people use filtered water and strong LED lights, very often, even though pH and everything else is perfect.
Get us a better picture and then to help you recover from this, answer the questions that have been posed to you by the other members and we will get you sorted quickly.