every one of your obervations was correct (btw I got to know the tabula recta as vigenere square [1])
kcovjgfktgevgf was the key for noqinylndnqysmwfacvjrrfj\n (and \n is indeed endoftheline)
I used an online vigenere chiffre "applet" (ok it is javascript so not really an applet but who cares) and I got an off by one (just define the alphabet as bcdefghijklmnopqrstuvwxyza or use jbnuifejsfdufe as the key)
PS. Without tor you can use [3] and thx for making me waste that 5 minutes :D it was fun
Don't know it isn't my puzzle. Maybe I'm wrong and this isn't the solution and there is still some way to go.
Edit: damn wanted to try the /999 but the site is down (yeah I'm using tor and not the onion.link link) I hope this is just the HN effect and it will soon work again
Edit2: I hoped to find something hidden in the image itself but it wasn't
Edit3: If anyone else wants to give it a shot https://blacklotus.github.io/ uploaded the index.html and vigenere.png (oviously no other files)
In the bottom left of the dark web map there is another puzzle that says to "visit when the :imer (sic) runs out" with a countdown that is at like -2600 days or so. Could be related as a previous or future step of the same puzzle.
It looks less ominous and more of a web-based puzzle to me. I've done something similar for 4chan's /g/ board back in the day setting up a simple puzzle with the "prize" being a bruteforced tripcode that was to Serial Experiments Lain. It was fun for the day and promptly ruined by the 4th or so solver who leaked the tripcode to ruin the little circlejerk that had formed over having solved the puzzle.
It also made me respect people who make complex puzzles. I had to recreate the puzzle several times because I had to create the puzzle in reverse and test that the solutions would work. It took me several attempts to get everything right and in the end the most difficult part of the puzzle was that the font I had used did not differentiate between a capital I ("eye)" and lowercase l ("el") well enough.
E: Here is the timer I was talking about and another page.
https://imgur.com/XXpyoqW