The blur effect is causing a really serious slowness on two laptops (medium range) especially on logout out and shutdown screens, the whole animations is too laggy and mouse moves hard between the action and cancel buttons.
I already reported the bug, but for now I disabled blur effect (with other slow animations especially that new maximize and minimize slow effect) and the situation is much smoother and fast for now, then I set panel to opaque, everything looks fine: panel, widgets, tray.. the only issue is thumbnails and tooltips on panel items and also desktop icons, with their background looking transparent it makes reading text much harder.
with blur off, tooltips and task manager previews often stay glass because they take alpha from the plasma style, not just the blur effect.
try System Settings → Colors → edit your active scheme → Tooltip / Tooltip Background and pick a solid color (full opacity).
if that still looks washed, switch plasma style once to plain Breeze and check again. some third party styles force translucent tooltips even when blur is disabled.
say which plasma style you are on if it still stays see-through.
yeah breeze dark still ships translucent tooltip SVGs, so editing color tokens wont harden them.
if you want solid pops without a third party theme, copy the desktoptheme and force the tooltip background:
mkdir -p ~/.local/share/plasma/desktoptheme/breeze-opaque
cp -a /usr/share/plasma/desktoptheme/default/* ~/.local/share/plasma/desktoptheme/breeze-opaque/
then open ~/.local/share/plasma/desktoptheme/breeze-opaque/widgets/tooltip.svg and set the tooltip background fill opacity to 1 (or drop the alpha from any fill-opacity on the background path).
System Settings → Appearance → Plasma Style → pick breeze-opaque, Apply, then log out once.
also check System Settings → Desktop Effects → Background Contrast is on. with blur off, contrast is what keeps the panel popups readable.
if it still ghosts, say plasma version (plasmashell -v) and whether this is X11 or Wayland.
Nothing worked for me, I don’t know why but I feel KDE Plasma is dropping support for low and medium range laptops with every new release, before 6.2 version the whole desktop was fast with all default animations and effects enabled, then came those changes for night light to improve what they call image quality, and night color became unusable even night mode works fine on Windows10, and with latest updates the blur effect became a nightmare, it slows animation on logout and shutdown screen, plus some animations like maximize and minimize windows became really laggy. For now, Windows10 is much faster and smoother than Plasma 6.7.
If the effects were working well before and it’s become laggy now with new versions, that’s not expected and is a regression. If that’s the case, please report it on https://bugs.kde.org with as much details on your hardware configuration as possible.
We actually try to make Plasma more optimised and easy-going on low-end configs, so I’m sorry it got worse for you.
I don’t think it was not expected, the night light problem is already reported since 6.2 version, and don’t know if they will revert change for low or old hardware, may be devs have powerful laptops and machines and cannot see how well optimized new added code is doing, with each new version some features are becoming heavy to run. I started using Plasma since 2020, it was a good experience and adventure, for now I’m thinking to switch to another alternative.
We have limited (developer) ressources and it may well be a very specific hardware quirk, which means sadly I’m not expecting the issue might be very actionnable (it could even be some low-level stuff happening on the graphics stack or kernel)…
