Square Enix's debut HD-2D title Octopath Traveler appears to have been delisted from the Nintendo eShop, but there's probably nothing to worry about.
Earlier this week, it was spotted that Octopath Traveler, the RPG that originally released in 2018 and introduced Square Enix's HD-2D style of graphics, had been removed from the Nintendo eShop. There was no formal announcement about its removal from storefront, so it obviously came as a bit of a surprise to some - the game is available on other digital shops like Steam still, so it's not like the game would be completely inaccessible. As pointed out by Gematsu, though, since at least December 2023, Square Enix has been listed as the game's publisher, where previously Nintendo was the publisher for the international release.
This might suggest that the game has only been temporarily delisted while some behind the scenes changes are being made. Without an official comment from Square Enix, there's no real way to know why the game is no longer available on the Switch eShop, though the game is still technically available digitally - you just have to buy a code for it from My Nintendo Store as opposed to the eShop.