Help needed please

So I'm going into week 3 of vedge atm.

As you can see by 1 specific plant the tips are going illuminous yellow, can't for the life of me understand why. I have 10 plants in total and have about 5 grows under my belt but have never encountered this.

On the whole the plants looks healthy bar that.
There are 2 others showing signs and the other 7 on track atm.

If you can give any advice it's appreciated.

What's your water like? And what are you feeding, and in what?

I get the feeling they are cold. What are your temps like?

looks like too much nutes and middle one looks like too much or too little water
whats your PH like?

Others are right, give us specific info on your feeding/watering schedule, nutrient EC, temps and also your lighting-what lights are you using, what %, and how high?