Automatic adjustment of files on import

I use ISO bracketing and raw files. So my camera stores the image as three separate files with ISO:
1000
1600

2500

Looking at the images in camera, there are clearly different light levels.
When I import into Lightroom Classic 12.3 (Camera Raw (15.3), the selection screen also shows these differences.
After the import, the three images are displayed differently for a second or two and then all are displayed at the same level as the  ISO 1000 image. The metadata, of course, shows the original ISO value.

I do not, to my knowledge, apply any settings during import.

Is there a Lightroom setting which could cause this to happen?

Andy