One of the seedling is not showing any signs of growth, you can see it in the picture (top left corner). Since this is an autoflower and it has already lost out on 2 weeks of growth I wonder if it is worth keeping it or use the space for another?
Alge growing is too wet and bad.
Chances are your soil is too compact and got root rot or seedlings can't get 02 to the roots. Loose airy soil and will fix your issue
bonjour
Malheureusement au bout de 2 semaines je pense que les racines ont pourrit ! dommage, ou profitez en pour utilisé l'espace avec une autre plantes, c'est ce que j'aurais fait, bonne culture !