Monitor port switches at every boot

Alma 9.3 running on a Dell Optiplex 7010 MT with onboard Intel HD graphics.
There are two DP ports and I have one monitor plugged in to DP #1.
I power up, see “welcome to grub” and some messages flying by (because I have quiet boot turned off), then the screen goes black. I unplug the monitor cable from DP port #1 and plug it into DP port #2, and there’s my prompt to log in.
Then I power off and do that again. This time it jumps back from #2 to #1 during the boot process. I’ve seen this on two different identical pieces of hardware. What the heck?