Euirectangular background rendering blurry

I rendered a room with the equirectangular feature in the camera (under ‘panoramic’) so I can use it as a world background. The image itself renders very well, but once I set it as an environment texture world background (with equirectangular projection) the output render is very blurry.
Does anyone know how to render a background image so it looks like it’s a “real” render?

What resolution did you render the environment texture to?
Mind you that an environment texture spans a full 360° view of the “whole world” around you. In order to stay halfway sharp and crisp, you will need a gargantuan image resolution. But even then it might still be lacking…

Another way might be to use the environment texture “just” for lighting and reflections and to render the image with a transparent background. In addition to that you render backplate images of the environment to add later in compositing.