@ben2talk How would I get to those specific QT settings? Mint has something called Qt5 Configuration Tool (aka Qt5 Settings), but I see nothing like your image.

This does look like a Strawberry/Clementine bug. I checked both applications against LinuxMint and Ubuntu (several versions) and S/C always uses that pale yellow background for tooltips. I could find no other application on LinuxMint that uses any similar tooltip theme. In fact, for the file browser in LinuxMint (Nemo) the tooltips don't change at all moving from light to dark theme (the background color is pulled from your theme color selection and the foreground (font) seems always to remain black). What other test might we perform to confirm this is a S/C v LinuxMint/Ubuntu bug?