Two stage GUI boot?

Can anyone shed some light on what I'm seeing, explanation below.

After I press the power on button.

I see a high resolution, looks like it's 3840x2160 (4K) Apple logo and a progress bar

Progress bar gets to about 1/3 of the way through the boot process then a black screen

Then a much larger Apple logo and progress bar.

Any idea why the two stage GUI boot and if it's possible see only a single before the login prompt ?

submitted by /u/ithakaa
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