I make the setup USB from scratch using built-in Windows tools.

Using recent NT6 admin CMD, enter DISKPART, select your proper (USB) disk, and use the CLEAN command to prepare the USB drive. Safely eject the USB and reboot.

Reinsert the USB and run Diskpart again, select your proper disk, and enter CONVERT MBR to prepare it for traditional widespread bootability. This writes a Master Boot Record up to the first 440 bytes of sector 0, leaving the small remainder of sector 0 blank to allow room for a primary partition table.

Enter CREATE PARTITION PRIMARY to make a single blank partition encompassing the entire drive.

Enter ACTIVE to make the selected primary partition bootable, or it's going to do no such thing for you in BIOS.

Enter FORMAT FS=FAT32 LABEL="yourLabel" QUICK which will quick-format the partition like any other FAT32 volume.[0] Fat32 was originally the minimal default filesystem intended for UEFI firmware to boot from. But NTFS containing a proper EFI folder now usually also works just as well with lots of firmware, so alternatively FORMAT FS=NTFS LABEL="yourLabel" QUICK is mostly OK too if there is a need for storing any single file which would be too big for FAT32. Either way will create a (hidden) original NT6 bootsector for that volume, either a FAT32-NT6 or a NTFS-NT6 bootsector respectively.

(Test-booting in BIOS to USB at this point - without any boot files on the volume yet - should show "An operating system was not found. Try disconnecting any drives that don't contain an operating system. Press any key to restart", which is a sign of potential progress. Otherwise less-generic approaches may be needed before going forward. Test booting by UEFI will not be conclusive yet.)

While in Diskpart your new (hopefully labeled) volume will now have an alphabetical "drive" letter automatically assigned and you should now be able to view its contents using the mouse in File Explorer, there should only be folders for SystemVolumeInformation and RecycleBin, if that. (Sometimes you may need to assign a volume letter yourself, which is easy in Diskpart or the GUI Disk Manager.)

Exit diskpart and you will be back at admin CMD line, which window can then be closed.

In File Explorer, copy the boot files (bootmgrs, BOOT folder, and EFI folder) from the mounted Windows Setup ISO, over to the target formatted USB volume.

(Test-booting in BIOS to USB at this point - with only boot files on the volume so far - will show "Windows Boot Manager / Windows failed to start . . . ENTER=OS Selection", and hitting Enter takes you to the Windows Setup bootmenu entry which is a sign of further progress. Test booting using UEFI shows "Windows Boot Manager / Windows failed to start . . . ENTER=OS Selection / ESC=UEFI Firmware Settings", also progressing to the Windows Setup bootentry. Otherwise, less-generic approaches may be needed before going forward.)

In File Explorer, copy the remaining folders from the mounted Windows Setup ISO, over to the target USB volume. That will end up with the entire contents of the mounted ISO finally present on the USB. But not the least bit dependent on the DVD boot process any more.

Full successful booting should now be possible, BIOS or UEFI on any truly decent mainboard. Analogous to how the physical setup DVD works.

Much simpler & quicker to prepare than it sounds. The most time-consuming thing as usual is waiting for the large install.wim file to be copied from the mounted ISO to the target USB.

For BIOS booting, the mainboard will read the MBR/partitionTable (sector 0) of the designated boot drive which will then direct the boot routine to the active partition's bootsector on that drive, which will then proceed to read the bootsector of that partition, which then reads the bootsector's designated boot files (very commonly) located on the root of that same partition. For BIOS these files are Bootmgr(s), the BOOT folder, and Bootnxt if present. Just like it always was for NT6 before UEFI.

Now also on the Windows Startup media for more versatility there is an EFI folder present so the drive can boot using UEFI without the mainboard needing to utilize CSM/BIOS. UEFI doesn't depend on a coherent MBR, "active" partition, volume bootsector, nor bootmgr (and its associates) in the root of the volume. Just finds a nice accessible correct EFI folder on a firmware-readable filesystem supported by UEFI on that particular mainboard firmware. The ideal mainboard can use UEFI to boot from MBR or GPT layout drives, having a valid EFI folder on either a FAT32 or NTFS volume. A defect sometimes appears when the USB drive needs to be layed out GPT-style to boot just because the mainboard UEFI firmware is garbage.

Oh, well, GIGO.

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[0] For "yourLabel" I like to use a descriptive abbreviation positively identifying both the drive and the partitionNumber on the drive, as a label for each volume. While keeping the volume label to 11 characters or less as nature intended. Like BLU8GB_P1 for the first (usually only) fat32 partition on a blue 8GB USB drive. Or BLU8GB_N1 if it was NTFS. Another ok labeling option is something like "W11_23H2v2" which gives you an idea of what is on the drive, but instead I still prefer to use the volume label to pinpoint the hardware, then put a more lengthy text file in the root on the volume, named appropriately to document what the software version is.

Unlabeled volumes autoidentify like "Local Drive (X:)" or "Removable Drive (Y:)" so don't let that fool you into thinking they are already labeled. I would take action and label them so they are less of an accident waiting to happen. Labeling can even be accomplished in the File Explorer GUI. Any time in the future that you plug in an unlabeled drive, you want it to contain the only unlabeled volume(s) you see.