When not using the blur effect, the logout screen can be barley readable (see attachment). Could you please make it darker? maybe 0.75 opacity instead of the default (?)
Created attachment 112284 [details] logout screen on bright background
This is actually not a problem with blur being disabled but with background contrast being disabled. I was about to file a bug right now about it. In the screenshot attached, you can also see that the unselected options (e.g. shutdown) are unreadable. This happens with all the themes I've tried (air, oxygen, breeze, breath, etc.)
Created attachment 117980 [details] Poor contrast of text of unselected log out options when background contrast disabled
This is actually: https://bugreports.qt.io/browse/QTBUG-70138 Since 5.16 we have a workaround = text is legible.