Welcome to the forum. If you can post just one picture under natural light. it will be easier for others to help you. From what i see. hard to tell under purple lights. is it looks like it may be a PH problem.
What soil are you in and what are you ph’ing too.
@Myfriendis410 is better than i am at diagnosing leaf troubles.
My ph is around 7.2 my soil is fox farm happy frog only nutrients i give is fox farm organic big bloom
The strain is greenhouse seeds white widow
Fox Farm soil you should be around 6.5 that’s probably your issue. A bit of lock out. But it’s super hard to tell with the Blurpies
Yet and 410 have ya covered though.
Update. Ph is 7.5
And i give my plants equal amounts of water my water meter says my healthy plant has moist soil but the plant with the issues has much wetter soil
Posted better pics
So, what kind of meter is that? One of those soil probe 3 in 1 meters? If so; they are almost worthless. You really need a decent PH meter and TDS meter to be successful. Good soil, but looks like a bit of nute burn though you are about 3 weeks in flower (I believe) so some older lower fans will start to get beat up and ugly.
If you could give us an overall shot of the plant in natural light; that would be good.
Phosphorus deficiency is what I’m seeing
Maybe wet feet too
3 in 1 soil meters work you just have to know how
Not too wet not too dry and clean the probes with scratch pad
Can you explain in detail how you are checking your Ph
Soil or water?
She’s going to need more than that. Big bloom doesn’t have much of anything in it. Really strange how she’s this far along into flower, with no nitrogen source, and still green.
The OP needs to provide more details
How old are they etc etc