what is your watering schedule you dont keep them this wet all the time do you ?
they should only need a good drink about once a week and let it dry out all the way then water again and those pots in the grass cant tell how good of drainage/oxygen holes you have
looks like you mix needs some perlite in for aeration as well
edit typo
Thank you for your answer...
That once peer week kinda shocked me, tbh.
I do not keep them that wet as you see in the picture. I just watered them like 5 minutes before photoshooting, but... I do water them 3 times per week :/
My thinking process was kinda like: "Oh noh, they are turning yellow, drying - not enough water."
Water drainage and holes are good, at least I think so.
Thank you again for you answer.