Hi Andrew,
Welcome to Microsoft Community.
I'm Hahn and I'm here to help you with your concern.
I'm glad to hear that the Windows 10 22H2 security update (KB5034441) issue was resolved for you! It's great that the security update downloaded successfully on the second try. Keeping your files and apps intact during the process is a smart choice.
This update actually requires 250 MB of free space in the recovery partition to install successfully. If the recovery partition does not have enough free space, this update will fail. In this case, you receive the following error message: 0x80070643 - ERROR_INSTALL_FAILURE
If you encounter any further issues, feel free to seek assistance.
Your Sincerely
Hahn - MSFT | Microsoft Community Support Specialist