This is easily explainable if you look at a whole chart for the past 5 or 10 years: https://tradingeconomics.com/hong-kong/exports

HK (and China) export always plunges in the month with the Lunar New Year Holiday. In 2022, that would be February, but in 2023, it's January, hence the large decrease. In fact, HK export this Lunar New Year is the third highest ever, only standing behind 2021 and 2022.