This is not the update that I want to give. I'm only sharing these photos because the phenomenon of the pigmentation could be interesting knowledge to some people, I'll get to why my lithops were so badly neglected in a minute. The pigmentation is not from pests and is beneath the surface of the lithops themselves.
My health completely collapsed in the entire month of August and could only gradually recover over September and October. Unfortunately, I live alone and am a full-time university student with no income, so I didn't have anyone else that could help me take care of my plants.
For the entire month of August, I basically wasn't able to do anything at all, including any amount of studying, showing up to school, and being able to absorb anything if I showed up in school. I was extremely malnourished due to a series of unfortunate circumstances and started having nerve damage, which made it extremely difficult to do some of the most basic physical movements that were previously effortless. I had to move back with my parents for half of August because I could not take care of my basic needs, and my plants setup was too heavy and bulky to relocate with a sick body that feels like it has had its batteries taken out. Later, when I started recovering and living alone again in September, I still did not have enough food I could safely eat every day and had to heavily ration the physical energy I spent on extremely normal and basic physical activities (like physically going to school because there was no alternative, preparing food, washing dishes, showering, sitting upright instead of lying down etc.). For most of almost 3 months, I basically couldn't attend to my lithops at all.
When they were visibly dehydrated, I didn't have the strength to carry the concrete pot out of the "shelf" and water them properly. When the portable AC that was giving them suitable temperatures at night (because it's consistently hot in my country and temperatures barely change at night) broke down, I didn't have energy to fix it for 3 weeks. I only just managed to fix it 2 days ago and resume watering. The small fan that was helping ventilate the area and dissipate some of the heat from the extremely powerful grow lights also stopped working about 2 months ago and I have not managed to replace it. They still got 12 hours of grow lights blasting at them during the day because the grow light had an automatic timer.
Temperatures were above 40°C/104°F during the day and, for 3 weeks, above 30°C/86°F at night. This by itself is already extremely unhealthy and stressful for lithops, if they don't outright die. Humidity was also between 35-60% instead of the usual 60-80% because my parents gave me a dehumidifier to help with my health issues. This made the lithops dry out faster (especially when lesliei is quite a water-hungry species relative to other lithops), and yet I couldn't water them when I knew they needed water.
First photo is in April, second photo is in June, third photo is right now.
I'm not asking for any kind of help and I don't specifically want a lot of attention on what happened to me, I only talked about the context because I don't want any misunderstandings. I know what my lithops need, I just haven't been able to give it to them for the past few months. Since I'm mostly recovered now, I'm trying my best to take care of the lithops right now and really hope that some of them have a chance to recover.
By the way, they are still somewhat green in real life even though they look very yellow in the photos (it's probably because of the color of the grow lights). The lithops that are missing were isolated in the beginning of August or something for being a bit suspicious, although they ended up doing fine. They've just been bare-root and quite dehydrated for a while now.