Thank you everyone for jumping in with some great replies. Truly appreciate it, can't say enough what it means to have peeps like everyone here willing to offer advice and experiences.
I scoped it this morning, and no pests were found. There doesn't appear to be much in the way of it having spread further, but that's tough to say.
I'm leaning towards cold damage or the LED being too close. Both seem very valid, and quick fixes to easily rule out.
I bumped the temperature 1 C on the heater, I may give it another slight bump, I'll be going 1 degree at a time... as it seems to operate on a temperature range.
I raised the light a couple inches, I'll readjust it tonight, I was in a hurry.
They really liked the new reservoir mix, almost half the tank was empty. I was expecting a flooded floor, but nope...looks like they liked it.
A slight rise of 50 PPM this morning, but considering they drank about 20L or so overnight I'm not too worried. But it also shows that I don't want to bump much higher then 930 PPM.
I re-ph'd to 5.8 as well as topped up with roughly 6 gallons of RO.
Since I was scoping for pests, I snapped a pic showing a leaf under magnification.
I'll have a complete update this evening after I go back out there.
Thanks again everyone, I can't say as it's something I've encountered before so I appreciate the help.