The defending champion said he quit as a “matter of principle” after being told to change his jeans.
Archived version: https://web.archive.org/web/20241229085023/https://www.bbc.com/news/articles/c98lkrdkz70o
SpinScore: https://spinscore.io/?url=https%3A%2F%2Fwww.bbc.com%2Fnews%2Farticles%2Fc98lkrdkz70o
Relevant links:
Emphasis on the third link, on what’s not allowed: sneakers, jeans, t-shirts. Under the claim that it’s “to maintain the high standards of the FIDE World Rapid & Blitz Championships”… yeah, nah, non sequitur.
And more importantly it shows that the dress code in question is NOT about decency, or preventing cheating, or not distracting other players; it’s all about “if you dress casually we’re going to be assumptive trash and assume that you don’t take the competition seriously.” No wonders Carlsen walked away from it.