All numerical data in Makie is internally translated to Float32 before being plotted. For scatter plots this happens here for example (Point2f0 is 32-bit precision).
From what I understand, the rationale is that GPU-based backends need the data to be in Float32 for performance reason, but this does create some problems in a few cases. For example, converting date times to milliseconds is another scenario where this introduces some annoyances.
I imagine that ideally the conversion to Float32 should not happen in backend-independent code (as it currently does) and the GPU backends should be somehow find a way to use the whole Float32 range for the plot by shifting data back and forth, but have no idea how feasible this is.