Today I restarted my Pixel 4 then running the latest version (prior to the 0824 update, aka android 13) after an auto update. I encountered the following 'bricking':
About 10 seconds after entering my passcode after the reboot, my phone restarted on its own. It booted into what I guess now is the other partition where I booted into a recovery screen that said my filesystem was corrupted and gave me the choice to factory reset or reboot. After rebooting and entering my passcode, my pixel 4 rebooted again after about 10 seconds.
After many cycles of this, I discovered the phone could sit indefinitely between rebooting to the lock screen and my entering my passcode. I reasoned the thing that caused the reboot must be something that is decrypted after entering my passcode, so perhaps the cause of the problem was isolated to my user. I went into settings and created a guest profile before my phone could restart. Then, after my phone restarted twice, I entered my password and switched into guest in that 10s window. After switching back to my main and only profile, the phone did not auto restart anymore.
This is not a permanent fix as my other system partition is still corrupted and unable to boot. The phone alternating between the recovery screen and the restart looping install I guess is the phone switching between partitions.
Please if you have encountered this problem comment below so this issue can get some attention. Thanks.