When searching text, I have the following buttons: ↑ Next ↓ Previous Next, search upwards, so in the less recent past, so it should be labelled Previous, and vice versa. Also, all the other KDE software uses ↓ Next ↑ Previous Reproducible: Always
This is intentional, since search starts at the back and then proceeds upwards. "Next" refers to the next match, not later in time.