is from the KDE Plasma System Settings -> Search -> File Search page. (Full screenshot: https://bugs.kde.org/attachment.cgi?id=139724)

The button looks very much like the text is cut off. The ‘r’ at the end seems to be the left part of an ‘n’. The horizontal spacing is much smaller than the vertical spacing.

is with Breeze widget style. Here the horizontal spacing is almost the same as the vertical spacing, so the text no longer looks like it is cut off.

I suggest to increase the horizontal spacing for Fusion.