Alt+tab window switcher visibility issue on Mint 20.3

[rcrx]

Tried all 3 versions of pro-dark-xfce (4.14, edition II, 1.6) and none indicate the active window with a highlight that's appropriately distinguishable. Only 1.6 was even noticeable and then only a mildly bolder font... this is not merely a nuisance but a usability problem.