Strange spots + leaves growing smaller and seems more fragiles. Maybe nutrient burn? Cause of RootJuice? For now plant is growin at norm rate, can save it?

I suspect the plant is evaporating more water than usual due to the heat, but it can't process the absorbed nutrient components yet. This will settle down, as can be seen on the young leaves. I would increase the humidity to reduce evaporation and thus decrease nutrient uptake through the roots at this point.

Hot soil or over feed usually when this happen water the as if the where seedling some plant don’t like nutrients where it organic or synthetic..

Hi yeah you can see when the ph squed on those few nodes and then grown out again try not to do what you did to cause that. I wouldn't saying environment or anything like that just shocked with nutes

This looks more like mutation or virus... In my experience any major issue with leaves i just toss out. You can wait and see if it grows out of it. mutations on early sets of leaves don't always stick around. i don't think virus are too common... if using same batch of medium with other plants without issue, helps eliminate that possibllity or makes it much less probable. I had a plant with wrinkly leaves that never went away.. little droopy, just not 'normal.' No other plant had an issue using teh same medium, so probably wasn't a virus, whic hleaves mutations on the table. I kept it, grew it out, and it didn't spread, which also pointed at mutation vs virus. It was a garbage yielding plant. low trichome density, weaker yield relative to canopy size etc... This is why i avoid mutations that drastically impact the leaves. A little variegation is fine, but major issues likely impact effectiveness of the leaf and that will cause a major domino effect more times than not -- just guessing.. makes sense though. Each to their own... try growing these oddballs out when you see them and form your own conclusions. I kill them off - severe mutations liek this, not mild ones. still worth another week or two of investment to see if it grows out of it. But, if you have any constraining logistics or scheduling realted concerns, slash and burn and replant.

Brown spots and discolorations can indicate various nutrient or environmental issues: - Calcium deficiency: Yellow or brown spots appearing on the leaves often signal a lack of calcium, which can develop due to improper soil pH levels. pH problems: Fluctuations in the pH level of the growing medium can affect the plant's ability to uptake certain nutrients, causing similar symptoms. Nutrient excess: Excess nitrogen or other nutrients can burn the roots, leading to discoloration and damage to the leaves. Edema: Improper watering or high humidity can cause edema, which can also create spots on the leaves. Suggestion - flushing, larger pot = better nutrient distribution, calcium (4) - magnesium (1) treatment, mild foliar feeding, replenishing micronutrients. I usually place a U-shaped plastic tube, about 2 cm in diameter with holes drilled in several places, in the pot for targeted nutrient delivery and root aeration.