SUMMARY
(this is on X11, not tested on Wayland)

When using the "open containing folder" action from a different program (tested with VSCodium, Jetbrains IDEs, and Firefox' download notification), the action only succeeds if none of the parent folders are currently opened within dolphin, else whichever parent folder is opened will be focused instead.

In other words, "open containing folder" on any file or folder within the directory /home/naxdy/git/some_project will only succeed properly if none of the upper level folders are opened within dolphin.

STEPS TO REPRODUCE
1. Open dolphin and point to /home/[user]
2. Download a file in Firefox (e.g. the HTML of this page)
3. Upon download, select "open containing folder" from the navigation's burger menu

OBSERVED RESULT
Dolphin focuses, and if there are multiple tabs, the tab pointing to /home/[user] will focus, but the containing folder (/home/[user]/Downloads) is not opened.

EXPECTED RESULT
Dolphin focuses and a new tab is created, pointing to /home/[user]/Downloads

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Gentoo 6.0.6 / 5.26.2
(available in About System)
KDE Plasma Version: 5.26.2
KDE Frameworks Version: 5.99.0
Qt Version: 5.15.5