why does this happen
Float truncation in the rendering engine. Basically you only have a limited number of digits you can represent in a computer number, and having like 8 digits before the decimal reduces the number of digits you can have after the decimal. A number like 100000000.1258 gets turned into something like 100000000.1 and you can visually see the lost 0.0258 as a point out of place. This effect got really pronounced with the update that removed maps and added shaders and apparently introduced less precision at some point in the rendering pipeline.
