You can try using the following command in the Terminal app to see if that particular update is still available (doubtful, but worth trying):
softwareupdate -l
If you see the 13.4.1 update in that list, then use the following command to install it making sure to replace <update-name> with the actual name of the update making sure to leave the double quotes in the command:
softwareupdate -i "<update-name>"
So if the full name of the software you want to install is called lets say Special Update, then the command would be (I don't know what the actual name would be):
softwareupdate -i "Special Update"
More than likely you will need to check for the full installer instead of the smaller update patch so if the 13.4.1 update is not available with the first command above, then use this command to look for a full installer for 13.4.1:
softwareupdate --list-full-installers
If you see the 13.4.1 installer in the list, then you can download it using the following command:
softwareupdate --fetch-full-installer --full-installer-version 13.4.1
AFAIK, this will only download the full installer app to the Applications folder. You will need to manually launch the installer from the Applications folder....the app will likely be called something like "Install macOS Ventura". If this is the name without any version number in the name, then I highly recommend you actually create a bootable macOS USB installer instead of just running the installer app. I have sometimes seen an older installer app automatically download the more recent update before performing the install (though I think this was when the app was automatically downloaded by the OS instead of using the command line). You can use the instructions in this Apple article to create a bootable macOS USB installer (disregard the download instructions in the article and just follow the instructions for preparing the USB stick and using the command line):
Create a bootable installer for macOS - Apple Support
Make sure to have a good backup before you do anything just in case something goes wrong.
Also, the "softwareupdate" command should prompt you for an admin password (or admin username & password) for some of the commands (especially ones to download or install an update).