Braune Spitzen

Your environment is way off. To hot and to low RH.

That's not too big a deal right now but hard to say for sure what caused that. I'm thinking either heat stress and the soil is too wet. From the looks of it, you are in 100 percent soil, you need to get some sort of aeration (pearlite,pumice,lava rock). and 86 is not too bad but at 50 percent humidity you plants are not going to be their happiest. at that temp you want to have your humidity around 65-70 percent. shes still young so they like higher humidity and will grow better if they are not too dry. Shes looking pretty good though. When you pot her up make sure you get some aeration in there. and i didn't not see a ph reading for the week,if you do not have a h meter deffs get one and gett your water 6-6.5. i did not do that on my first grow and I was chasing problems because of it. you dont have any really issues right now so that gives you time to get one. and something to adjust your water. i wasn't phing my water then i measured it it was like 8.2...really bad