I have a fan extracting to the attic. Scrubbed of course. Temps stay around 80 when the light is on.
MG organic soil with no additives except 1tbs of blackstrap molasses per gallon of water all through flowering till flush.
Really? Nice! Coincidentally I'm using MG organic potting mix, and I've had some issues with too acidic pH and some nutes being locked out, specifically cal-mag (calcium causing little spots, sometimes rust-colored or brown that spread and worsen more so near the top/middle of the plant, magnesium on the bottom fan leaves, which starts with yellowing around the edges, which then browns and spreads closer to the central vein of the leaf and eventually towards the petiole).
Maybe if it's strictly potting soil it's a bit different than the mix, and if you amended with something like dolomite lime or something like that then it'd make sense if no issues have popped up, and it would have most likely started to happen closer to flowering, as typically is the case.