This is likely due to precision loss at high values, since position can only hold 3 32 bit floats (or in the case of Unreal 5+, 3 16 bit floats.)
To fix this, you need to enable large world coordinates in your world position nodes. This system localizes position vectors to greatly expand its limits. However, this system was only introduced in UE5, so you would need to upgrade engines to 5+ for this solution.
Note that this does come at an added performance cost, so only enable this if you are seeing the artefacting.
If you want to read more about LWCs and how they work, take a look at this documentation from Epic: