The accusations came following k0nfig's FACEIT account being hacked on May 15, with the hacker themselves posting messages on Discord about the Danish star's previous allegations of a VAC banned account.
Dust2 reported on these allegations in 2017, in which it is stated "one of the Danish players at one of the top 5 Danish teams [...] some information has emerged about a VAC ban within the last 2 years. It's pretty serious."
The Danish player in question turned out to be k0nfig, and it was claimed that an account of his was VAC banned in 2014, and that Valve knew: "There is something about an account that belongs to k0nfig, which has the ban [...] this is only a rumor so far, it is reported that Valve is aware of it, but has chosen to ignore it."
On May 15, 2019, the hacker who gained access to k0nfig's FACEIT account claims that they used the same email and password to login into the VAC banned account in question, which previously used names such as "kR1ST1AN" and "k0nfig".
The post, which was made on subreddit r/VACSucks, also includes a video of the hacker using k0nfig's passwords to log in, as further evidence.
At the time of writing, k0nfig has not addressed the accusations, however did Tweet "There’s so many idiots on this planet" after as the accusations surfaced, although it's unclear what this was in reference to.
There’s so many idiots on this planet. 😝— Kristian Wienecke (@k0nfigCS) May 15, 2019
Valve's precedent on previous account VAC bans is fairly clear. Brazilian player VSM was banned from the CS:GO major circuit indefinitely due to a VAC ban on an account he had in 2013, when he was only 13 years old.