U.S. online holiday spending is expected to grow at its slowest pace in at least eight years, as product shortages, higher prices, and lingering pandemic-related uncertainties threaten to put a strain on the shopping season. Adobe Analytics forecast an average 10 percent growth or $207 billion in online sales in November and December, compared with a record 33 percent jump in 2020 when people chose to shop from home, instead of traveling to stores during the pandemic. After grappling with virus restrictions on stores for the better part of last year, retailers are now dealing with a slew of pandemic consequences including a clogging of global supply chains that could lead to a shortage of everything from Nike shoes to Apple iPhones during the holiday quarter. The lack of clarity around what items could run out of stock, and when, is making it hard to determine whether product shortages could …