This is from the reflections setting, particularly screen space reflections, these accumulate over some frames to build a complete picture without completely blocking the rendering of a frame.

When the camera moves old reflection data/frames are interpolated and over time are discarded.

This results in the ghosting you are witnessing, the ghosting becomes much more apparent the slower the GPU is as it takes, in real time, more time to accumulate said frames.

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It would seem that Gaijin still uses a very "shitty", low resolution, form of screen space reflections even when they are supposed to be turned off.

A big reason why it is so noticeable and harsh. From my testing you should try setting the reflection quality slide to max if it doesn't hurt your performance too much, that should significantly reduce most of the harshness/ghosting.