brettpaul So, when you start your phone, you will be asked for your phone SIM. There is only a single phone SIM prompt. Once you typed the SIM code, you get the black screen with only an unlock symbol. You click that unlock symbol. Now you see the animation for one passphrase prompt open, and half a second later you see the same passphrase prompt open animation play again, as if two passphrase prompts opened on top of each other. You swipe back on the passphrase prompt currently showing on the screen twice, first to close the keyboard, then to dismiss the whole passphrase prompt, only to find there is actually a second passphrase prompt waiting for you behind it. If you would swipe back on that one twice too, now you are back to the black screen with the unlock button. Clicking the unlock button again will this time only open a single passphrase prompt, and swiping back at that one twice will bring you back to the black screen with the unlock symbol.
Have I understand exactly what you are observing correctly?
In that case, I cannot reproduce it on my Pixel 7a. I see only a single passphrase prompt opening animation, and after swiping back twice, I am back to the black screen with the unlock button.
Please confirm the above is exactly what you are observing, or make any corrections as needed. Then we can ask someone else with a SIM with PIN and passphrase login to try reproducing it on a 9th series Pixel instead.
Likely graphic glitch unique to the 9th series Pixel, but if it is, several or most people with this setup should see it.