Could not find a reference/posting on this, nor a config to control this behavior - but does not feel like a defect:

- Recently jumped from Konsole 17.12.* to 19.12.*
- New Tab behavior has changed
- Old behaviour: a new tab would open adjacent-right of the currently active tab [...][current][new-tab][even][more][existing][tabs]
- New behaviour: a new tab opens at tail-end (right) on the tab bar [...][current][even][more][existing][tabs][new-tab]
- I personally liked the old behavior