Anyone know what this is?

Tips look to be taking slight osmosis damage (high ec). This means that the medium is at its salt capacity or getting close and the salinity is getting high. Why is it important? Water likes to flow in direction of highest salt content when separated by a membrane. Inside the plant there are nutrients (salts) all over, in order for water to flow efficiently Into the plant the medium needs to be less "salty" than Inside the plant. Osmosis is a driver of turgor pressure, tugor pressure controls guard cells Inflation or deflation. Which is a driver of cell elongation. Stomatal Coductance must happen before photosynthesis can occur. When ec gets a little high it means your adding more salts over time than the plant is using up, they are accumulating, plant is using what it needs but leaving excess, as it builds the pH can skew depending on ratio of existing nutrients in the soil. If I was a betting man I'd say your ph is starting to skew from too many salts (high ec). As soon as you engage ph and ec there is no point in thinking of nutrients until you get an idea of where your medium sits with ph and ec. Whenever I see lime green all over with no obvious starting point its micronutrient, micros are mostly effected when ph peaks over 7, combined with high ec, nutrients are jist struggling to uptake and bind, which presents as nutrient deficiencies. Leech medium till ec drops within range 1.0-1.5, then ph to 6.5 and start fresh with a balanced fertilizer suited to your stage of growth. Once you got ph and ec in range then you see if problem persists, adding nutrient salt prior will probably exasperate the problem.