Agree on ph, Mag seems to do better with slightly higher ph, or slightly higher every other watering. But since mainly on new growth the easiest solution is probably to back of the light a bit and/or raising temps to consistent 81-84F.
I will say i've been through about 10 runs and never seen this before and although i've changed a lot of things the one thing I'm doing different is
no tap water and the bell just went off.... chlorine. ? will be adding some Tap tonight... checked my ph this evening and I'm at 6.0 .. good there. I put a small 200watt space heater in the box with my inkbird wifi temp controler.. its at 77degF at the lower levels and 84 up top. plant is happy and jumps when i hit refresh in the cam. leaves are perking up though were never really down.
TLDR .... not only have i been running a low pH but i think my temps have been pretty low too.. ambient basement temp is 64f or 17.7c . thats pretty low so my air intake and res is @ 64deg and the only heat on board is the light... even the ballast is not in that room so my temps read 80 at the canopy under the lights but its much cooler just under the canopy.. pretty sure thats a complicating factor and interestingly if i turn down the light i turn down the heat and visa versa. last run was even cooler but the growth was not as rapid.. more coco,. I've had many runs in coco with 350ppm tap water and never had this, same setup same temps. (in coco then). anyway thats it... Mg S chlorine problems from ph, source water and cold temps. think i've heard of cold temps locking out mg at like 62f somewhere before? i also stopped using PowerSi bloom this res and also mammothP and Orca because i suspected one of those products was causing my ph to drop daily. i have another cab and its ph rises. could be root rot.. i do have some weird floaters but 64 is pretty cold for rot. hydrogaurd etc. roots should be fine. feeding about 2 min every hour, once at night. may have been feeding 30 seconds on every 15 min for a week thrice at night. was def feeding at 1 min every 30 min for a while..
I know TLDR.. im probably good from here out. going with low ph, low temp, no chlorine causing a Mg/S and chlorine problem .
