You can't create an new yii\web\Request instance in general.php because Craft isn't fully initialized yet. It worked in previous versions but the Craft team seem to have changed the loading order.
You must find another way to define you site base URL.
My guess is that your bucket doesn't have the right permissions. Try adding this permission to your bucket (use with caution since this will make the S3 100% public):
A compatibility issue with Craft 3.4.1 and maybe earlier. Running PostgreSQL12+ (PgSQL12+) couldn't finish Craft's installation setup.
I have no idea what change in PgSQL12+ could cause this behavior but downgrading PgSQL12 to lower versions like PostgreSQL11 worked as expected.
However Craft's docs states that PostgreSQL 9.5+ should meet Craft’s server ...