ok lot to say try to stay with me.
auto-flower huh... the first thing my mentor told me about auto-flowers was to not grow them . So I dont i learned they are lite feeders you dont have a ppm meter to know what your feeding at so you may have started to burn them up earlier and it kind of looks like it in the pics. Probably didn't add any kelp to help root development so you have that its ten weeks old hardly any roots its already flowering. I veg for months you have a small plant don't get to worked up about it as you aint going to get much so it isn't that big of a deal this is good learning for you so it isn't a waste. So anyways feed it at about 1/4 strength of recommended of the label then feed it at 1/2 strength in mid to later weeks of flower. No ppm meter means your just guessing at what your feeding it. What I said about ppms earlier you can cut all that in half since they are autos.
FFof worst soil out there you need microbes to break all that down. Microbes are your friend research what they do.
cal mag is an additive just use that at 2ml per gal when you do use it, mag is a better option as they like the mag a lot, cal mag is ok each has their roles.
Switch the light to 18/6 just about everything on the planet needs a rest period, the plant does a lot of things during the rest period research what that is. Like grow roots for one thing. Your in flower now so root development isn't on the plants mind but switch it to 18/6 for other reasons too like translocate resources.
Plant looks like it has a lot of sativa in it so that imo makes it even more of a finicky eater and likes a certain ratio of nutes, gotta learn how to read a plant. Plus being an auto you have to bring your A game.
You have to accept that you may be doing everything right (your not) but that its just a really hard plant to grow that needs certain requirements that you havent learned yet.
Whats the water source get a ppm meter whats the ppms of just the water ....that counts toward ppms it isn't at the right ratio of nutrients but the ppms count and ppms are whats important. Point being if your going to continue growing autos then maybe a cleaner water source like R/O would be better since autos are lite feeders.
Go on the ytube and watch all the harley smith videos ...don't be so stoned you cant remember anything. Then watch them all again. Lots of good growing channels on the ytube weed is a plant learn how to grow a plant...then apply it to your plant. Then once you get it down and everything is on point and you know your doing things right whenever theres a leaf spot you just ignore it and move on knowing that its just a minor thing, an issue the plant is going through and I don't need to fret about it as everything is going good in general and I will have a successful grow and stay the course instead of trying to correct an issue that i cant control.
Research nutrients, kelp, don't use kelp when it starts to go into flower, humic acid, microbes, mag, rest periods of plants and what it does, growing requirements for auto-flowers, there's a skill to just watering a plant so you don't get dry spots in your medium, lots to learn about and it takes time.
Get a better light.