Problems in composing a 4k environment by putting together 2k footage

I am trying to compose a small town in a 4k environment, by putting together 4 pieces of 2k footage of different houses. But once I've exported the total 4k composition of the town, I tried to zoom in on one of the of houses, and there is a reduction of quality compared to the original 2K footage of the house.
Why is that? Is there a special way to do this?

Greetings from Denmark

LSP wrote: I am trying to compose a small town in a 4k environment, by putting together 4 pieces of 2k footage of different houses. But once I've exported the total 4k composition of the town, I tried to zoom in on one of the of houses, and there is a reduction of quality compared to the original 2K footage of the house.
Why is that? Is there a special way to do this?...

If you mean a 2x2 split screen, each composed of a 1920x1080 frame, provided your project is 4k and is exported as 4k, the resolution of that exported file should be roughly equal to the original 1920x1080 material if viewed at the same equivalent magnification level. There may be some scaling during output so some small differences could exist, but it should generally look about the same.

By default the project will assume the characteristics of the first clip added to the timeline. If that clip is 1080p, then the project will be 1080p and you cannot export 4k. Make sure the project itself is actually 4k. If not the solution is create a new project using Custom Settings, and manually select 4k resolution, or select the current project and in the inspector, click Modify and alter it to 4k.

If you can describe more specifics we might be able to give more advice.

Dear Joema
thanks for your reply!
I found out that the spatial conform was set to fit.
Now it works.
Best regards from Lasse