New Windows 11 installation on another disk DESTROYED my veracrypt bootloader

what to do now ?
I have a veracrypt (1.26.20) system partition on NVME disk (Win11 Pro 24H2). The entire drive is encrypted and i boot with a password and PIM. It was all ok until i decided to install a new fresh Windows 11 on another SSD (Win11 Home 24H2) . Now let me explain what's happening:
since i know Windows is a lame system, i USUALLY disconnect all other hard drives when i install Windows on a new drive, because i don't want Windows to modify existing partitions. I then boot the drives separately by selecting them from the BIOS/UEFI boot menu. I've always done this, but now there's a new problem: NVMe drives. They can't be disabled from the BIOS/UEFI (this is crazy !), and they can't be easily removed (you'd have to remove the heatsinks from the motherboard). So i decided to leave it connected.... terrible choice.
Once the new Windows is installed on the other disk, upon reboot, the VeraCrypt bootloader starts. Afterwards, once i've entered the password and PIM, Windows' dual boot option starts, asking me which operating system to choose. If i choose the usual, already encrypted operating system, the boot continues without problems. If, however, i choose the new (unencrypted) operating system, the system RESTARTS and i have to enter the password and PIM again, and then it proceeds with the booting of the new operating system. And here, the first problem has already arisen: entering the password and PIM twice for an unencrypted operating system, crazy !
And now we come to the most serious problem. Even though i didn't like the double password reboot situation, i let it slide since both systems continued to boot without problems. UNTIL i updated the latest system (the non-encrypted one). Having installed the July cumulative update on Win11 Home, now the system, when restarting, does nothing but go into Windows automatic repair, and despite offering me a dual boot, i can only boot the latest system, but not the encrypted system on the NVMe disk !!!!! Even after pressing F11 when starting the PC (BIOS/UEFI Boot Menu) and selecting Veracrypt Boot Loader, only Windows Automatic Repair starts !
I admit i was scared. After a few tests and reboots, i couldn't boot the encrypted disk without physically disconnecting the SSD with Win11Home. Now i've managed to boot the encrypted disk and everything works as it should, but the other disk remains disconnected and i don't know what to do.
What i'd like to do is completely separate the two disks and disable dual boot. I'll choose which disk to boot via BIOS/UEFI.
What should i do ? I know i need to modify the EFI partitions somehow, but how ?

I don't remember if the entire NVMe drive is encrypted or just the system partition (C:).

[Edit] Correction, only the system partition C:.

... i have similar issue, just mail-subbing.

I do not know if it related, but when i cloned a drive, it had everithing cloned including the disk IDs. I had to use the USB bootlable little companion software of the macrium reflect to regenerate the disc's id to be able to recognisable by the software-part-of-the system as a whole as other disk. (and there were some other settings >> i mean there are accessable, just logic based layers, so do not give up)

It does not involved NVMe-s, or maybe not even veracryp (i forgot ), but it was the similar "i can do anything, it boots only from the unvanted drive"-situation.

My issue/goal would be similar than your's: dual windows OS, one with veracrypt, but i would like to be able to reach the unencrypted withouth any password what is related to the encrypted.
Since you are too -passively- confirmed: the veracrypt password is needed to the windows-change, i might need to go to bitlocker, or maybe for a hidden volume. (i wrote this maybe you have seen something and can comment on something)

Again: if it worked before for you, i think it is only a missing ID, or an overwrote order somewhere.

There is an interesting discussion here, though, in hindsight, not conclusive:
https://forums.tomshardware.com/threads/can-i-disable-nvme-slot.3752830/#post-22629795
In my opinion the best answer is dwd999's.
The method I use for this relies on having sufficient external storage to store an image of the nvme drive: I use the free Macrium software to image the nvme drive onto a usb drive; I then use Gparted to delete all of the partitions on the nvme drive so that it is totally unallocated; then I install Windows 11 on my ssd alternate drive; finally I restore the image to the nvme drive. This allows both drives to be booted through bios and function independently, and has worked successfully for me for the last year allowing me to go through the Windows 11 beta period without any problems. Since I do not keep much on my nvme, my Macrium images are only around 30GB each and I have an old Samsung 970 Evo Plus 1TB m.2 in a Sabrent enclosure as my usb external drive. So you could try this if you have sufficient external storage or even if you have another ssd that you're not using.

The problem for us is that we use Veracrypt.
What programs currently support backup and recovery of Veracrypt-encrypted drives/partitions ?
I think gparted ? I used it once with truecrypt i think. In Windows environment instead ??

What i'd like to do is completely separate the two disks and disable dual boot. I'll choose which disk to boot via BIOS/UEFI.
What should i do ? I know i need to modify the EFI partitions somehow, but how ?

I finally solved the problem (there are more solutions). Here's how:

There are 3 main methods to achieve the goal.

1) full disk encryption (not recommended; Disk not recognized, accidental overwriting by Windows, dual boot/Linux issues, etc.)
2) physical disconnection (dismounting everything may be complicated/difficult, especially with NVMe heatsinks with thermal pads)
3)Deleting/Restoring partitions (disk wipe)

Another method is to disable NVMe drives directly from the BIOS (only a few manufacturers offer this option, such as Alienware) or disable the PCIe lanes connected to them.

I chose the third method, as already suggested here https://forums.tomshardware.com/threads/can-i-disable-nvme-slot.3752830/#post-22629795 .
Make sure to completely erase the NVMe disk/delete all partitions on the NVMe drive, so that it is completely unallocated.
After the NVMe drive is no longer recognized by the Windows installation media, you can install Windows 11 on an alternate drive; encrypt the system partition (optional) and then disconnect it from the computer, or, if you have another NVMe drive, create an image of it and then erase it.
You can now restore the first NVMe drive with a previous disk image or install a clean Windows operating system and then encrypt the system partition (optional). Now reconnect/restore the other system drive.
This allows you to boot both drives via the BIOS boot menu (F11) and have them operate independently.