This problem generally occurs on the POS body that has been used for a period of time, because the long-term use causes some debris like dust to cover the POS machine magnetic head, so when the card is swiped, the magnetic strip of the card body cannot contact the magnetic head well, resulting in a swiping error.
For this reason, we recommend that you use a piece of hard paper with moderate hardness and gently drag it horizontally and vertically in the card reading slot to erase the dirt of the magnetic head.
The card may be a magnetic stripe card, and then read the card as a chip card, so let you switch to a magnetic stripe card.