In the wild, a plant sits in veg until the sun starts to move to and gives it less light. This triggers flower, then the sun continues to move lower and lower in the sky reducing the light as the plant moves through the different stages of flower. By the end of flower the plant is getting less and less light. Once you flip to flower reducing the light will help mimic outside growing. Usually for me my highest light intensity is at the end of veg and the first two weeks of flower, after this I slowly raise the light lowering the light intensity as the plant shows signs of light stress. Since this is happening every time during flower I wonder if you are reducing your light the further you get into flower?
I was having the same problem as you, for ten grows always issues mid to late flower. After many of hours talking with people on here and trying different things, what worked for me is this. Less light, less feed, and less water volume during watering.
Sadly at this point all your leaves are affected and will be difficult to get her trics to turn amber. Pull the light way back she is getting to much. Reduce the amount of water you feed with, try to get your dry cycle down to 3 days.
Also if you are pH'ing your water I would pH it to 6.0, 7.2 is very high. I am not familiar with
happy frog but if it regulates the soil media the you should probably just quit pH'ing, if it doesn't then yeah drop that to 6.0.
