Non-isekai light novels or anime that gives off false impression that it's might be isekai,but it's not really isekai because characters didn't die in Earth and reincarnated in fantasy-like another world or got transported in another world via supernatural phenomenon such as magic summoning ritual,pure coincidence or by will of another world's god.
Just like how pseudofossils are inorganic objects, markings, or impressions that might be mistaken for fossils,pseudo-isekai is how you should call an non-isekai anime or light novels that gives off so many wrong and false impressions that cause people think it's isekai while it's not.
Sword Art Online is not an isekai. Virtual reality is part of science fiction genre,not isekai genre. While SAO has multiple arcs involving characters having journeys in different virtual worlds,characters weren't transported by magic or die and got reincarnated like in Rising of The Shield Hero or That Time I Got Reincarnated As a Slime,therefore,SAO is pseudo-isekai,which is how i call non-isekai works that looks isekai,but they are not really an isekai.