NEW YORK—Buoyed by solid hiring, healthy pay gains, and substantial savings, shoppers are returning to stores and splurging on all types of items. But the big question is: How much will supply shortages, higher prices, and staffing issues dampen their mood this holiday season? Americans, already fatigued with pandemic-induced social distancing policies, may get grumpy if they can’t check off items on their holiday wish lists, or they may feel disappointed by the skimpy holiday discounts. Exacerbating their foul moods is the fact that many frustrated workers called it quits ahead of the holidays, leaving businesses short-handed during their busiest time of the year. Shoppers are expected to pay on average of between 5 percent to 17 percent more for toys, clothing, appliances, TVs, and other purchases on Black Friday this year compared with last year, according to Aurelien Duthoit, senior sector adviser at Allianz Research. TVs will see the …