Looks like photo bleaching .its more common now with leds .it does not hurt anything except looks funky .I run super high ppfd and get some on occasion my gg4 has a little its running close to 2000 ppfd though .once its there it stays but you can run lower ppfd to reduce chance of getting it
Probably light burn yes, solutions :
- Higher lamp
- Better ventilation
- Colder temperature
- CO2 supplement of 100 PPM for each 100umol/s over 1000umol/s || [>! Never over 1500 PPM !<]
( ex: For 1400umol/s == 1400 PPM of CO2 )
- Or you can use something like a string to low your branches. ( or super-cropping if it's before week 4 of flowering )
Good grow bro 🦜