Not to say it isn't Dess, but I think it's a fairly important detail that people are reading in around 7 years of fan fiction speculation when they're saying it's "clearly" Dess, while also omitting that Dess is potentially the one lost in the Game's code and featured in the easter egg during chapter 3 from putting 1225 into the gachapon.
Actually just looking at the game itself it's not actually "obvious" that Dess is the knight.