Need advice from experienced autoflower growers on the effects of Cal-Mag deficiency and the effects of stress

One 24 hour period of no light or a slight deficiency will not cause a harvest to be drastically different. Auto or photo is irrelvant to this. Though autos are generally weaker plants to start, so any less than optimal outcome will draw them down further than a photoperiod due to lower starting point on average. That is an overt N-deficiency. Maybe, there was a misdiagnosis? Auto or photo is irrelevant, again. They really aren't as much different as most perceive, anyway. The trigger to flower is 99% of the difference. Maybe, some potential carryover from ruderalis evolving in northern latitudes, but the ruderalis genetics as a whole are severely reduced in autoflowers when made correctly, so assuming they have all of those traits is a false perception of the peanut gallery. You are not providing enough N in this picture provided and no signs of either Ca or Mg problems - at least not seen from this far. But, the N-deficiency is screaming, 'help!' People that think autoflowers are drastically different are confusing cause and effect. i joke about them being wearker, but even that is not so huge of a difference at this stage. Miscellaneous: Stop foliar sprays. either going to cause mold onen day or clogging up stomata which will impact CO2 intake -- a much more important limiting factor than just about anything else. Light and carbon are the first priority to worry about and shouldn't be skimped on for the benefit of other things. Wet plants invite pathogens. Roots are for nutes and stomata are for transpiration. A foliar spray can be effective at deliving nutes to a locale, but this should only be done in extreme contexts that should also be 100% avoided with basic competency. When healthy, foliar sprays are a form of masturbation... makes people feel good but doesn't do much for the plant. Calcium deficiency -- yellowish-brown spots that will probably start near the top but not on the top leaves -- has some mobility. Magnesium deficiency -- rust colored spots along with interveinal chlorosis. This will be mid and lower part of the plant as it is a bit more mobile, i believe. The other key difference -- when you see visible symptomsm of Mg deficiency, it's 4-6 weeks delayed from the actual physical deficiency. So, when you see it, any fertilization adjustments for 'next time' need to start 4-6 weeks before you saw the symptoms to be most effective. The point is, these are 2 different problems. There is no such thing as a calmag problem. you can have both a ca and an mg problem, coincidentally, but it is not a calmag problem. You can use other products than calmag to mitigate each. epsom is a good source for Mg, for example. calmag tends to be diluted and makes you buy a shit ton of unneccessary bottles over time. Incorporate something like cal-nitrate and you'll never have a calcium problem nor a need for "calmag" at all. it's like watching people ram their head into a brick wall and deciding to do it again, and again, and again... if a formula doesn't provide enough, adjust the formula or use different brand of products that do a better job etc...

Plants are resilient. Give them what they need and they can be very forgiving. Good luck

Your plants are also showing signs of being starved of nitrogen. If you're feeding your plants, then it's probably a pH issue, rather than lack of nitrogen

Calcium and magnesium are important. Calcium builds cell walls which are how buds are made. You can correct the cal mag deficiency and everything will be fine. Your plant will want extra cal mag around week 3-4 of flower to build and swell your buds. Just stay on top of it and it should all be ok.