What is happening to my cuttings?

Hello community,

I am getting back at being concerned about my plants

And I am wondering why my cuttings, which were successfully rooting in summer, are now rotting one after the other in spite of daily solar lamps. Should I give them a round of hydrogen peroxide bath?

I’ve put a lot of efforts in them so I hope to see some reach spring.

They all are in water and close to a window.

Thank you in advance