If the window background is opaque, the text color's translucency is ignored. If the window background is translucent, the text is completely transparent and shows what is behind it.

A line-edit's placeholder shows the problem clearly. With Fusion, the text doesn't have translucency.

P.S. I tried to attach a Qt Designer file several times but got "Jira could not attach the file as there was a missing token. Please try attaching the file again."

EDIT: Attached the file after creating the report.