Before I saw your post, I was indeed about to ask "When did the word 'culture' replace 'entertainment'?"

In my country, where the same phenomenon happened ('divertissement' is now labelled 'culture'), I would say it was less than 10 years ago, perhaps closer to 5 years ago for a systematisation of the use.

During Covid-related lockdowns and other limitations, it reached new highs: how dared we limit access to the vital need which 'culture' is, how dared we forbid 'culture' people ('culture' producers (!)) to work for some time, and so on.