Correct units to use while plotting mollweide projection of sky chart with RA and Dec values, matplotlib
With stars extending to &plusmn;90&deg; on the horizontal axis and rather sparse near those limits, I suspect that RA and Dec are swapped.
Try this instead:

plt.scatter(df['rarad'], df['decrad'], s=1, color='red')

Also if you want the plot to resemble the night sky, filter the star list by apparent magnitude, and reverse the horizontal axis so it increases from right to left.