I tried to do an apt update, and all repositories under sources.list.d have some errors. For example:
https://repo.bullseye.elive.elivecd.org bullseye InRelease gives GPG Error (It is "not signed")
The spotify repository i manually added following the official guide which has always works returns "NO_PUBKEY"
No PUBKEY either for Index of /debian bullseye InRelease
What did i break?
Edit:
May it be due to the "upgrade" installation process that turned this Ubuntu installation into elive?
well all those keys should be in 'etc/apt/trusted.gpg.d/' ... so check if they haven't been deleted in some way.
Else you'll have to import the keys again.
Or maybe this is biting you (depending on how old the installation is):
This is what I have under such folder, i guess they are there?
How can i re-import them?
As explained in the link in my previous post. 
In short: wget -O- <https://example.com/key/repo-key.gpg> | gpg --dearmor | sudo tee /usr/share/keyrings/<myrepository>-archive-keyring.gpg
I sort of thought that you were still on Bullseye but clearly you already shifted to Bookworm... In which case probably the easiest method would be to upgrade using the Elive-iso again.
Spotify would need a manual reset though.
On a sidenote:
On my machines (whether Bullseye or Bookworm) 'apug' works just fine. So it isn't the repos.
I don't think it should have been the problem, maybe looking at your installation logs there could have been any clue, but I think you didn't enabled them so I don't see the reports in the server
I would rather install the bookworm version (torrent on Patreon) instead 
which is much newer and improved in many aspects, try to do an over-install of it with the bookworm one
Tried this, didn't workout!
That's what i wanted to do, but i accidentally boot in legacy mode, ignored the mbr warning, broke grub, restarted the live usb, and at this point elive didn't detect elive itself anymore and neither detected the elive partition as an "upgradable" one lol
Luckily nothing really went lost since everything is in my nas anyway ahah
Fresh installation works great
The installer actually did not ask me if i wanted to share informations like it usually does. I always enabled it for elive know where the data goes.
Did use that one! In fact i have elive retrowave installed in a pc, but i wanted to replace ubuntu budgie on my secondary pc using the fresh iso. I just tried the upgrade mode to move from ubuntu to elive because "why not". And then that problem appeared. On the other hand, overwriting everything like i just did getting a fresh installation, returned a well working system
In case something could've been lost: Get a 'grub-boot-disk' and let it find the partitions for you.
Once booted you can repair grub from there.
Booting in the correct mode (EFI) and reinstalling Elive should have solved the issue too, on the other hand since the previous install was unsucessful i think the installer considers then it to be a new clean install 
unless it asks about which option to select
Didn't really take few minutes in the end... by here's my recap:
Everything is fine now
