Online sales hit record highs$1.2 trillion globally and $282 billion in the U.S.over the holiday season, but high return rates could hit strong profit margins, according to new data from Salesforce.Holiday shoppers have already sent back $122 billion in merchandise, according to the data that was aggregated from more than 1.5 billion global shoppers. That figure could eventually grow to $133 billion, says Salesforce.Retailers had a robust holiday season, but a 28% rise in the rate of returns compared to last year is a cause for some concern, Caila Schwartz, Salesforce director of consumer insights, said in a blog post.Part of that high figure comes from an increase in consumer behaviors such as try-on hauls, which is when people buy massive amounts of clothing and record it for social media; and bracketing, which is buying extra sizes above and below the consumers standard size.Salesforce argued that retailers should invest in artificial intelligence solutions, like AI agents, to make the returns process easier and more tailored to specific customers. For sure, the company is building its own AI solutions for retailers. It says that 75% of U.S. shoppers are interested in using an AI agent to complete returns and exchanges.Retailers who have embraced AI and agents are already seeing the benefits, but these tools will be even more critical in the new year as retailers aim to minimize revenue losses on returns and reengage with shoppers, Schwartz said.Despite the high returns, the strong sale season was boosted by surges in mobile and social media commerce, in addition to increased consumer spending, according to the data.