SUMMARY
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When I right-click on "Konsole" icon and select "new tab" it opens a new Konsole window instead of a tab in the existing Konsole window.
It seems similar to bug #373440, but this one is really old so I preferred to open a new bug report
***

STEPS TO REPRODUCE
1. Open a konsole windows
2.  Right click on Konsole icon in the "start bar" or in the menu
3. Select "open new tab"

OBSERVED RESULT
It opens a new window

EXPECTED RESULT
It should open a new tab in the existing Konsole window

Operating System: RebornOS Linux (Arch-based)
KDE Plasma Version: 5.26.4
KDE Frameworks Version: 5.101.0
Qt Version: 5.15.7
Kernel Version: 6.0.12-arch1-1 (64-bit)

I've asked in the KDE matrix group and it seems confirmed also on Konsole 22.08.3/Plasma 5.26.3, yesterday git master.