What’s going on here

[Lemonginger]

Hey everyone, first time grower here. Currently I’m running 3 purple lemonade autoflowers from fast buds. For the most part it’s been smooth sailing so far but I do have a question about one of the plants leaves and could also use some help diagnosing why my leaf tips are yellowing on another. I’m running a mix of ocean forest and happy frog in 5 gallon container. I water roughly half a gallon every 4-6 days depending on when the pots feel dry. I haven’t fed anything besides water phd between 6-6.5.

So my question here is what could cause the leaf tips to look like this? Is it a mutation or something I did?

Lastly, does this look like a nutrient burn or what could be going on?
As always I appreciate everyone’s feedback! Happy growing!

 

[Lemonginger]

Currently on day 24 from sprout