Some functions would return either bytes our text (in python 2 parlance, strings or Unicode) depending on the input. People would call decode on text (despite it only making sense on bytes).

Ultimately Python 2 encouraged a programming model where if you just tested with ASCII everything worked but the instant one of your library users put in an accented character or a kanji everything would blow up.

Just to make things clear: many python 2 programs operated on bytes thinking they were text. There isn’t really a way of resolving this API without user intervention on declaration of intent (not saying 3.0 was perfectly right but not every change can be made backwards compatible if you still have existing code)