Yellowing Leaves

My plants are in the 5th week of the vegetative stage. Growing in Pro Mix HP and using grow micro bloom from advanced nutrients. The lower leaves are going yellow and dying. This is my first grow and I’m struggling to know if it could be nutrient deficiency or nutrient burn or even some other issue. I’ve attached a few photos.

Need a whole plant pic in natural light..

I've come up with two possibilities have you checked under the leavesfor bugs and it might be a little over fed sorry for the shitty pic and the best of luck

IMHO the ones in the small pots look like they're rootbound, and maybe a little overwatered. Roots in small pots can only suport so much vegetative growth, basically once the roots have filled the pots, for every new leaf produced, an older leaf must die. I'd start by up-potting them.

They look to me like they’re in flower but are supposed to have been photoperiod seeds. I have them under 18/6 light

May be contacting the seed supplier

If they're on a 18/6 thoses are autos.. Looks slightly overfed, new growth looks good..
I'd just pluck off those leaves and carry on.. Older shaded leaves do die off..