I somewhat expected this, because it's a Sony game that was likely to use PSN, but this means Marvel Tokon is now on a very short list of fighting games that don't work on Linux, including 2XKO and the online mode of Dragon Ball FighterZ.
For what it's worth, the issue isn't the rarity; it's the scope of impact and undermining of the integrity of the product.
For highly competitive games, even the ability for players to say "there are cheaters, I know there are, and so I think that person is one of them" is a long-term sentiment drain that is not trivial. There are internal research numbers on what exposure to a single cheater does to players' perception of game integrity and trust in the fairness of their experience, and it's really really bad