It is important that the base of a dry stone wall is created correctly. At least 1/5 of the height for flat stones. The base should be set carefully so that the wall can be built with a 75 ° slope. https://youtu.be/mNmIrHSSvEc Round stones can also be used sporadically, but must be supported on the back.
There are several weak points here. You can see a V-shaped incision that opens to the front, behind which stones are placed on round bollards, which are inclined forward and look like a sliding layer. Due to the pressure on the hillside, the wall slipped further and further over time until it collapsed in late spring of this year.
