That looks less like a mystery disease and more like the plant is pulling mobile nutrients out of the oldest leaves now that the auto has kicked into flower.
Top growth still looks fairly green, so I wouldn’t panic or start dumping a bunch of stuff on it. But at 4-5 weeks on an auto, yellow lower fans usually points to the soil not keeping up with demand, especially nitrogen and general mineral availability. Same thing happens with tomatoes when the root zone is a little underfed or watering has slowed the biology down.
I’d want to know what soil you’re in, what you’ve fed so far, and how often you water. If it’s just bag soil and plain water, I’d do a gentle top dress with worm castings/compost and a mild organic dry amendment, then water it in slowly. Don’t try to make those yellow leaves green again, they’re spent.
Also if that pot is clear/translucent, I’d slide it inside an opaque bucket or wrap it. Roots and rhizosphere life don’t really want light on them.