That's the level of detail working as expected. Photo mode and menu cutscenes use the highest level of detail, and gameplay uses several lower levels of detail based on distance to ease the graphical load and allow the game to move at target frame rates. The geometry of the suspension of the lower part of the car will be considered a low priority because in the normal cameras of the game they are elements that are rarely visible, so it is normal that in a LOD1 parts are simplified or eliminated.
In the future it is expected that Polyphony will implement some variation of virtualized geometry (an advanced tessellation) that should avoid sudden changes in the number of visible polygons, but until then (a GT8 or 9 on PS5 Pro or PS6) those changes will be visible if you look for them.
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In computer graphics, level of detail (LOD) refers to the complexity of a 3D model representation. LOD can be decreased as the model moves away from the viewer ...
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