Smartphone sales in China fell 13% year-on-year during the month-long 618 shopping festival, as brands raised prices to offset higher memory costs, according to data from Counterpoint Research.Sales declined from May 26 to June 21, with all major Chinese brands except Huawei posting double-digit drops as fewer promotions compared to last year weighed on demand. Honor sales dropped 33%, while Xiaomi’s fell 24%.Also Read: Apple's China smartphone shipments drop 6.7% as Huawei surges: ReportHigher memory prices amid a rapid build-out of AI infrastructure have pushed up handset costs this year, leaving brands with less room to offer steep discounts during…