What do you think this is? Beginner Grower in need of help. Thanks in advance!

First, I will provide what I am using and will explain the situation after.

Info:

Strain - ILGM Northern Lights Autoflower.

Pots: 5 gallon cloth pots (2 plants). One plant in a smaller pot (I thought about putting this one outside but decided to throw it in the tent.

Soil: Foxfarm - Ocean Forest.

System Type: N/A

PH of runoff: Plants are 26 days old. Mostly used spray bottle to keep soil moist. Just started to actually water them with a watering can a week ago. No runoff yet. Afraid of over watering in the beginning

Water Type: Distilled

What is strength of nutrient mix? EC, or TDS: Not using nutrient yet - the soil should provide enough nutrients for the first 4 weeks (or at least that's what I heard and going by)

Indoor Grow: Spider Tent 2’x4’ w/ Spiderfarmer SP2000 LED Fixture

I believe this 200W - I dim the fixture down to 80%

Temperatures:

Day: 75-76°F @ 70% Humidity

Night: 68°F @ 60% Humidity (I'm usually asleep at this time - I’ll do this different at my next grow)

Light / Dark (hours) 18/6

Fixture Height: 24” above plants

Ventilation system: AC infinity - Cloudline T6 (6”) exhaust fan w/filter

I have the temperature/humidity probe at the same height as the top of the plants

Setpoints to start exhausting at 71% humidity & 79°F

AC, Humidifier, De-humidifier,

I do have a humidifier & dehumidifier. At the moment the fan is taking care of the space really well. I’m not running either the humidifier or dehumidifier right now.

Issue:

On day 23 I started to notice some of the leaves are turning yellow / spotting on one of my plants in the 5 gallon pots. The other two are looking fine. I’m wondering if I should be worried about this. Please see the attached pictures.

I don’t think it's a nutrient or a watering issue. The leaves seem to be pointing towards the light fixture , almost looking stiff where the other two plants look very relaxed and happy. So my original thought was too much light and stressing her out? I did turn down the dimming to 75% and moved the plant to another location, but she’s looking the same.

Another thing I read up on was maybe variegation? I’m just perplexed because it's just one of my plants. I find myself reading so much I think I need to take a step back and ask a question.

I appreciate any comments and thank you again.