I would just throw this out here after you finish this plant and all the others you grow.
Don't shake it out gently cut into 4 pieces and take a look several here can work with those pictures.
Chasseing your tail was a thing I did twice then I read about half of seamadians posts.
You have a something went very wrong with your chemistry and it magnified with something in your media.
You will find rust red areas in the middle of your root ball if I am right, root rot in its beginning stages..
I have been growing for a very long time and still cut every one up if you have root problems and they pass into root bound and rot nothing you can do will change that once your into
Moab. If your not using that read a bit.
If your not adding a clean up your roots additive at mid veg and then flip. Read you will find a lot of your info right there.
If you want plants that finish like a race horse only roots will take you there all the chemistry is just college boy bull. You are growing from the top down and that is not how it grows.
Most of the heavily inbreed strains and anything that might be related to the white. The only way to get over the C- is to start a I. V. and main line it.
If you use
Cal-mag you need so much that you will have a Ma++ and not good and most have never seen it.
So get some Calcium and make a 5% to start with and spray every other day for a week and you should see results then slack off the mix if no results go to 6% and so on.