MapViewModel.cs

        public MapSpan Region
        {
            get => _region;
            set
            {
                SetProperty(ref _region, value);
                OnPositionChange(value);
            }
        }
		
		    private async void OnPositionChange(MapSpan mapRegion)
        {
            if (_lastSearchPosition == DefaultPosition)
            {
                await SearchByLocation(Region.Center);
                return;
            }

            var distance = _lastSearchPosition.DistanceTo(mapRegion.Center);

            if (distance >= DefaultDistance.Meters)
            {
                await SearchByLocation(mapRegion.Center);
            }
        }