In the Danish PowerPoint 2016 (build 1710 - 8625-2132) the English word "Tabs" is translated into "Faner" which could be right but not in this case (A and B) where it should be "Tabulatorer"—like in Word ;)
Reproduction : Click 1> and 2>, change (A) and (B).
This is valid for both textboxes and text placeholders.
May also be valid for earlier versions of PowerPoint.