Typo, should have been .tk - reason being for so long they were the cheapest, or in some cases free, which led to a long history of abuse being associated with the TLD. Incidentally, there's a bit of this in .to as well, so perhaps a Freudian error.
Both ccTLDs fall into the same category of "small company that sold out / got sold out to a scammy sorta-free-domains service", and both of them carry the same stigma as a result.
In Germany, .to-Domains were associated with warez/torrents, independently of the technology actually used to transfer the files. One of the most famous streaming websites in the German speaking web was kino.to and the domain kept its reputation.
They used to be given out as a free redirect like 20 years ago so all the spam/garbage/etc sites had some random url but advertised “random.to” as their url. I had many many free like name.forumsbb.com that I advertised as name.to
