How is the sweep type affecting the Bode plots for the same AC analysis in LTspice?
The type gives you the amount of points where values are calculated, and how they are distributed. Then in the plot they are connected by lines.

Using 10000 points linear over 20Mhz gives a point each 2kHz, which seems to be about right given your plot and start frequency.

The first half of your plot is just two points then because it is plotting logarithmic