Booting Windows on nvme takes 15 minutes, SOS

I use Qflash in bios to update my giga board, get a usb & format it Fat32. It pretty easy, if you're on 23 do 25 next, then 30 & so on.
Here's the support page for your board with bios'...
GA-AB350-Gaming 3 (rev. 1.x) Support | Motherboard - GIGABYTE Global
And a pretty straight forward YT vid, it's older but it's to the point & nothing has changed...
How to update motherboard bios AM4 X470 Gigabyte - YouTube

Should note any giga bios with a letter after it is a beta bios...looks like full support for yours ended at F41. There's normally not too many issues with beta's but you may wanna do some googling b4 flashing one & see if anyone else had issues using your hardware.

Thank you very much for your patience and sorry for the long delay, I have been busy and in the free time I've been researching more information for this 15 minutes boot.
1) from my researches, most comments around the web seem to indicate that the best version of the BIOS for my machine's configuration is the f25 (as the latest are made for newer processors), therefore I may not be that far behind with f23. I couldn't find any evidence online that f23 had a slow boot issue for anyone else. I could still do the update, but I thought I'd wait to be sure that it is necessary.
2) I have noticed something else: The 15 minutes of wait will happen BEFORE the windows OS selection screen IF the problematic system is set to "default" in the boot manager. They will happen AFTER the OS selection IF the newer Win installation is set as "default" in the boot manager (only when the old system is selected). I wonder if this means something.
3) booting in safe mode didn't make a difference
4) sfc, dism and 'superficial' chkdsk don't report anything wrong. (I haven't tried a "chkdsk /r" just cause I've read it could create damage if not used properly, so I'll do it if you think it's a good idea)
@zinou thank you so much for offerning to check the trace! Here you can download the compressed file: WeTransfer
It seems to have recorded only 135 seconds from what I can tell, but of course you'll know how to interpret it much better than me.

Also I have noticed that on the Malwarebytes forums they have a few successful threads where they guided people to the removing of KMS activators, so if you think it's a good idea, I can try to make a thread there as well. Please let me know.
Thank you again for your kind help!

- - - Updated - - -

Hello, sorry for the second update in such a short time, but I just verified my theory. FAST STARTUP does indeed conceal the issue of the slow boot!!!!
Fast startup doesn't seem to work in dual boot on my machine for some reason (maybe it's normal, I wouldn't know), so I did the following:

-unplugged the new ssd -> no changes in the boot time
-removed the second windows option from the boot manager (through msconfig) -> no changes yet
- re-enabled hibernate through command "prompt powercfg.exe /hibernate on" which I had previously disabled in my various attempts.
And there you have it, fast startup makes the computer boot in seconds.

@dalchina I'm tagging you just because you said that fast startup made a difference just for HDDs. Apparently it does also make a difference in Windows installations that are behaving weird on startup!

Now I guess one of my options would be to keep Fast Startup active, and just sadly give up on my idea of dual booting. ;_; But while I'm not ready to give that up yet, I also want to note that my short-lived dual-boot adventure brought to light a serious flaw in my Windows installation, because I am fairly sure that booting shouldn't take 15 minutes even with fast startup disabled.
So I still consider this problem unsolved, and I would love to receive further assistance if you don't mind.
I hope that this new information is useful somehow to the troubleshooting.

@Megahertz you have kindly suggested in another thread that I might try to do a "Repair Install with in-Place upgrade", do you mind if I ask you another question in that regard? (or to anyone else that will be so kind to reply, of course)
The page you linked says: "The installation media (ex: ISO or USB) must be the same edition and same or newer build as your currently installed Windows 10. If it's not, then the repair install will fail."
My system says it is build 17134.590, but if I can find a 1803 ISO build, it will most likely be 17134.1, I believe? Will 17134.1 be ok, or do I need to find exactly the 590? x_x
And if I mess up and the ISO version is not correct, will it fail before even starting the installation and leave the system alone, or will it go through and cause damage?
(My thought behind wanting to reinstall the same build, is mostly not wanting to add more variables to the problem, if it makes sense... as all my drivers are also from that build's period in time...)

After a while, I've finally managed to get some help and do the repair install with in-place upgrade to the same build (1803). It's been a couple of weeks since then, and I can confirm that the problem of the slow boot is gone. I lost just a couple of settings (mostly my realtek equalizer profiles were gone, and the restore points), but I retained everything else and didn't have to reinstall my softwares and drivers.

Many thanks to Megahertz for suggesting this solution to someone else who had the same problem of slow boot. Although I feel a bit disappointed for the unequal treatment: just because I mentioned having a broken activator, nobody even cared to suggest this simple solution to me. By the way, the activator was simply gone just by using a regular antivirus, and my system is still legitimately activated with my legit code.

For the future reference of those who encounter this kind of slow boot issues: I believe this problem might come from some kind of very lowkey and undetected Windows incongruity, possibly caused by a Windows update. A repair install in-place seems to fix it for most people. At this point, I'm led to believe that for those who might be facing this problem often, it may be safer to disable the windows updates completely, and just update their build through in-place upgrade. Just my piece of mind, of course.

I have a few more questions on dual boot setup, but I suppose it's better to open a new thread for those.
Thanks to everyone. I'll let you know in case the problem manifests again.