Okay, problems had to arise
Yesterday I did a CCC bootable backup, but on my spare HDD (not SSD) that I had. Everything went well, EFI was copied etc.
I am still on Catalina 10.15.2 (I had to change the name of my internal disk to Catalina, it was still Mojave from before, I also changed the "Mojava - Data" to "Catalina - Data"). Later in the night I decided to install Little Snitch because it is something I started using on my macbook pro meanwhile and I wanted my Hackintosh to catch up all the new things I had on my macbook. I also switched on the iCloud Desktop and Documents so my Hackintosh would match my Desktop and Document folders from my macbook pro. After installing little snitch I had to restart, which I did, and on the boot screen I wondered, hey lets try that CCC bootable backup you just made.
First thing, it seems to work, but it's extremely slow like I thought it would be, thus having a SSD was indeed a necessity. So I decided to reboot it because after login it was stuck on an empty screen with just my Desktop background. After that I booted back on the internal MacOS Catalina disk, but now I have this forbidden sign... and this error message when booting in verbose mode :
View attachment 472321
I havn't changed anything on my working build, no update, no changes to any kext nothing so I don't understand what happened. For information, I tried to boot back on the HDD now connected to a 3.1 USB port, and slow it is but it seems that I'm getting my access to the desktop with app icons and folders...