What makes you think he has bugs? I'm just wondering because I didn't see any tell tale signs and i'm always looking to learn more
The reason I am/was leaning towards bugs is the shape of the disfigurations on the leaves. Sucking and chewing bugs of the undersides of the leaves tend to leave the same markings. The problem was also spread throughout the leaves and small branches dying back at the stem, another place chewing insects love to start.
Heat certainly can and could be a problem being somewhat enclosed and not getting the full benefit of cooling breezes in that kind of heat. I tend to look for the most common problem first, heatwaves you have to grin and bare it outdoors, bugs are a constant threat and usually the culprit in outdoor soil grows. Ph in soil usually isn't the problem IMHO in most grows especially that late into the grow. Defs sure it could be that, but before I upset a balance of the plant correcting something that isn't the problem, thereby creating more problems like nute lockout, I just choose to look for the simplest and most common solution first.
Hope this answers your question, wasn't saying it wasn't or couldn't be any of the listed things in other posts.
Happy Growing