No, GNSS constellations are indeed usually in MEO, not LEO.
Using MEO means that they'll need fewer satellites for global coverage at acceptable elevation angles than they would in LEO, and since navigation signals are very low data rate, power is usually not a limiting factor either.
Using MEO means that they'll need fewer satellites for global coverage at acceptable elevation angles than they would in LEO, and since navigation signals are very low data rate, power is usually not a limiting factor either.