Production of Apple’s flagship iPhone 13 smartphone fell 20% in September and October, below previous forecasts.

The Christmas quarter is one of the busiest for the tech giant as many consumers buy its products as holiday gifts and Christmas is just around the corner.

Apple chief executive Tim Cook had previously said the impact of supply chain problems would be worse in the holiday sales quarter than in the previous quarter.

For the first time in more than a decade, the assembly of iPhones and iPads has been suspended for several days in China due to supply chain and power restrictions.

Also in September and October, the reallocation of the shared components put even more pressure on iPad assembly, resulting in about 50% less production volume than planned, while forecasts for the production of older iPhones also fell by up to 25%.