Discolouration and age

hi there Marky, that looks like a pH fluctuation that happened at some point. In soil you should be following water, water, feed , water water , feed .... get it? then check you pH, especially if you're using additives , often times the kelp-based extract like rhizotonic will raise your pH... to make sure it doesnt get much worse, cut out that additive. Then add beneficial bacteria like bacilus subtilis to stabilise it long term. Hope this helps ! 🚀

Can't tell much of anything with that light, I can see something is going on though, and if I had to guess an age I'd say Week 4 or 5 of the Flower stage, the plant is showing trichomes.

Does it matter how old it is? Without pictures of the entire plant, age is hard to guess. Also, pictures taken under "blurple" lights makes it near impossible to see anything. Please take some new pictures in normal light and then and only then, can an accurate opinions be offered. Cheers,...... Organoman.