Double xl Watermelon Weddingcake Autoflowering

This week I had almost no time at all due to family commitments - I'm also completely at a loss as to what deficiency my plants are suffering from. I would say a serious calcium magnesium deficiency. But why? I mixed every watering with calmag - I suspect that the pH value in the soil was not right at times. The deficiency came overnight with the second compost tea. Oh well - I hope I can still salvage something. I would be very grateful for help. Thank you 🙏