Just want to add my findings regarding IO issues during boot that may help someone. I am seeing the same issues on my new hardware (Intel 12600K running on MSI PRO Z690-A DDR4). I ruled out the USB stick right away as it continues to work fine on other hardware.
I've narrowed down the IO issues occurring during the copy of rclone -> /sbin/rcloneorig . The file is 80% copied and the USB drive is reset. This appears to be a timing issue with something going on in the background at the time the copy takes place in my setup. I added a 10 second wait just before the copy and that resolved the boot issue:
if [ -f /boot/config/plugins/rclone/install/rclone ]; then
sleep 10
cp /boot/config/plugins/rclone/install/rclone /usr/sbin/rcloneorig.new
mv /usr/sbin/rcloneorig.new /usr/sbin/rcloneorig
chown root:root /usr/sbin/rcloneorig
chmod 755 /usr/sbin/rcloneorig
version=`rcloneorig --version | head -n 1`
fi;
Tough to diagnose this edge case since it could be a factor of hardware, number of plugins loading, etc. Hope the helps others that might run into this.