Thanks cscs for your help.
I tried adding MODULES=(i915) to mkinitcpio.conf. The flickering persisted. But strangely, the boot screen looks a little better. Before, the screen would just show the three blinking dots near the upper left indicating it was booting. I always thought that was a weird looking boot screen. Now it shows the Dell logo, the three dots, and the word “Manjaro”, centered.
Then I tried i915.fastboot=1. Unfortunately the flickering is still there.
I then looked through my BIOS options, but didn’t see anything that looked like fastboot, so I didn’t change anything.
So the flickering is still there (though the boot screen looks nicer!).
Thanks