Plants looking bad all of a sudden.

It seems like a clear case of nutrient excess. The excess salts have blocked the roots, and they can no longer absorb the nutrients present in the soil. The only solution is to perform a root wash (2L of water for every L that the pot holds); if your pot is 11L, prepare 22L. I recommend taking it to the shower and draining all the water there. Prepare water at pH 6. + 'Flush' solution (Final Flush from Grotek or Canna Flush) https://thgrow.com/es/grotek/3528-final-flush.html this way you can wash the roots and clean the salts that are obstructing absorption in the roots. Remember: Adding more fertilizer doesn’t mean better quality. Good luck, my friend!

Hi! I have very little experience in growing on soil but to me it looks like overwatering and the roots are not getting enough oxygen. Did you let the soil get dry before adding more water? Cos it is important to let the soil get dry from the lower parts of the pot too and not just from the top and then water thoroughly.

Could be overwatered looks like the start of root rot. Could also be ph or ppm make sure it dries out then flush.

can the problem be the lamp being too close and hot?