Before 19w08a it used to display "Old graphics card detected; this may prevent you from playing in the future as OpenGL 2.0 will be required". As of 19w08a the message will display like in the attached picture. When coming back to the main menu from a world, the text is displayed correctly again.

This one is difficult to reproduce. You'll need to run the game on a rendering device that will trigger the warning.

Some analysis shows that this related to changes on the loading screen - the text is localized before the language is loaded.