The whole effect seems to have changed quite a lot. Hard to tell without a direct comparison, but I think the windows are much smaller in the new arrangement.
Is there a list what settings are changed for the effect, so I can try to find out how to configure it to be like it was used to be before?

I think in that effect, previously the name of the window was across the thumbnail and not below and thus probably the thumbnail was largers as the space for text + padding was available for larger thumbnails.

I wonder if there could be added such things as options in the menu where one selects if the arrangement should be a grid or natural. Adding something like "natural (maximum thumbnail size)" or in general thinking about a few more layouts that may suit different use-cases (e.g. many windows, often different windows, always the same windows, etc.).

Overview has an option to not blur the background, but Overview is different from Present Windows.

I guess we should keep the scope of this bug on the blur effect.

But I think what is actually making the experience worse for me is, that the windows are displayed smaller and the mouseover effect seems to be more subtle. I think some parts are just something one should get used to, but smaller windows in the overview is something that may even be seen as regression.

It looks like the window management got a larger overhaul with this upgrade and there are still quite a few rough edges. In Bug 457457 I reported another quite annoying problem without a clear way to reproduce / a complete description what the actual effect I am observing is.
Currently many things in the WM seem to have changed. Is there some list (possibly a bit more focussed than a commit log) what were the major changes and how they are motived? This may be helpful to improve the bug descriptions and/or find own ways to work around the problems I am currently encountering.

The Blur effect also isn't involved here. Overview and Present Windows' background blur doesn't turn on or off based on whether the Blur effect is turned on or off.

> that the windows are displayed smaller and the mouseover effect seems to be more subtle
Windows' size should be barely changed in Present Windows. The mouseover effect has been fixed for Plasma 5.26; see Bug 454842.

> Currently many things in the WM seem to have changed. Is there some list (possibly a
> bit more focussed than a commit log) what were the major changes and how they are motived? 
There's the release announcement, and my blog at pointieststick.com, but other than those, not really.

> The Blur effect also isn't involved here. Overview and Present Windows' background blur doesn't turn on or off based on whether the Blur effect is turned on or off.
I've seen that one of three related effects has the blur switch and this one does not.

> Windows' size should be barely changed in Present Windows. The mouseover effect has been fixed for Plasma 5.26; see Bug 454842.

Quite a few things seem to take more space now. I am not sure about the margins of this effect, but I think they increased. But having the label below the window with its padding probably shrinked the windows as well. You can have a look using the video button (nice function by the way!) for the overview effect and see how the windows are packed much tighter in the old version.
(You may need to look now, I don't know if the video is shipped with KDE or retrived online and may get updated to the new version soon)

I don't think I am seeing Bug 454842, as it has the same padding between the windows in both screenshots. I think the old effect had a slight zoom in effect on mouseover. As said this is probably not the most important thing (I am not sure about if it should have more contrast yet or if this is a thing the plasma theme has to implement), but it is annoying when the window contents are harder to see because the thumbnails are smaller because of more padding.

> There's the release announcement, and my blog at pointieststick.com, but other than those, not really.
I follow your blog, but didn't see a too big announcement. Only the usual nice incremental improvements. Thank you for the blog, by the way!

Created attachment 151116 [details]
Screenshot of the "show windows" effect with three Firefox windows

Here is an example screenshot with the areas highlighted that probably had less padding before.
With the "closest" layout you can also see a lot of padding, even where there is no text.

I guess some is there to make it visually more appealing, but the amount directly affects the size of the thumbnail and thus how much of the content you can still recognize.

Sorry, I think the bug got quite a bit out of the original scope. I created Bug 457492 for the layout problem. One may or may not add another bug for how the background is displayed.

Being able to disable blur in Present Windows is a legitimate feature request though. Let's keep it open.

> Being able to disable blur in Present Windows is a legitimate feature request though. Let's keep it open.
I thought about a new one without the "what things changed why I can't find my windows as fast as before" discussion.

Bug 457495 ;)