The growth of China's cross-border marketplaces could cause headaches for Amazon, but it should generate near-term tailwinds for Meta. That influx of Chinese ad revenue should buy it more time as it expands Reels to counter TikTok and updates its advertising algorithms to circumvent Apple's iOS changes. It also reveals how Meta still generates revenue from Chinese companies even though its social media platforms have been banned in mainland China for the past 14 years.