There are always tricks circulating to slow down supermarket cashiers. The banana and the bun trick has been circulating online for some time.
The bread roll trick is also a popular trick at Lidl. Anything that costs the cashier more time and nerves to their own advantage is not exactly nice. But not all supermarket customers are so elbow-like. The trick was probably "invented" and first made public by a Twitter user in 2019. The old tweet got more than 2,000 "likes" and hundreds of shares, as well as rows of comments.