There must have been a major quality problem with my finished mixed soil. According to the publisher, the producer did not ferment the product properly and therefore it only ferments in the pot. This results in the earth becoming hot and the plants burning. It looks like this is exactly the case for me right now. Now I'm a little unsure how to proceed. Either I hope they get through it or I get them out of there. The question remains whether it would be worth it.
Of course I don't want to withhold the pictures from you.