An American friend recently told me of a reunion with the son of the German family whose home he had lived in for a year as an exchange student. My friend had spent the year acquiring fluent German, which he spoke to the family.
The reunion, several decades later, took place among a crowd who were speaking English. Afterwards, the German son said to my friend: “I never realised you were witty.” Because in German, he never was. It was too hard to joke in a foreign tongue.
Anyone who has learnt another language will be familiar with this. We are more ponderous in our acquired language. We are slower on the uptake, having to construct each riposte in advance.