I think this is an intended feature, but it should probably stop selecting items, once the user manually changed the selection.

As above I believe this is an intended feature of Dolphin.

Germano, if you would like this to be a feature it can be turned into a wishlist item, please confirm.

It is not working properly regardless of whether the behaviour is intended or not, because Dolphin behaviour is not consistent
Let me explain with two examples that *have different behaviours*:

1)
In this video https://youtu.be/JpA_K6W0ohc you can see that pasting a lot of files causes just a few of them being selected/highlighted. Note that I did not touch anything during paste process. If you cannot reproduce, try to paste from a slow device like a USB drive.

2)
[2-a]you are copying a lot of files, like
1.jpg, 2.jpg, ..., 100.jpg
from a slow device like a USB drive (it's easier to see the problem with a slow device)
[2-b] you are in the destination folder while the files copy is in progress, and let's assume that in that moment the system is copying the 50th file (50.jpg)
[2-c] while 50.jpg is being copied (together with other files), you start operating within Dolphin on other (already existing) files in the same folder, like
a.pdf, b.pdf, c.pdf, ..., z.pdf
by selecting/highlighting them.
[2-d]So since you have manually selected/highlighted some files, Dolphin is not selecting/highlighting new files that are being pasted. But as soon you "release" the selection of files by clicking someelsewhere, Dolphin will start selecting/highlighting new files that are being pasted *after* that moment, so files from let's say, 60.jpg to 100.jpg. If we want Dolphin to highlight pasted files it should do that with all file from 1.jpg to 100.jpg, not just a subset of them


System details:
dolphin-20.04.1-1.fc32.x86_64
KDE Frameworks 5.73.0
Qt 5.14.2
xcb windows system

Thanks for re-confirming and the video link as well.

Confirming on Dolphin 24.02.0 - Plasma 6.0.3 - Qt 6.6.2