When Piranha Plant launched for Smash Bros. Ultimate, some players were quick to find out that their save data was corrupted after using the character in All-Star mode. After that, Nintendo did their own testing and couldn't replicate the issue. This left many wondering what was causing this major problem. While we don't have a 100% definitive answer, it seems like a specific microSD card might be the troublemaker.
Users on Reddit have come to discover that the Samsung 256GB 100MB/s (U3) MicroSDXC EVO Select Memory Card with Adapter (MB-ME256GA/AM) seems to be the reason why save data is getting corrupted. Here's the thing though. It appears the microSD card might actually be a counterfit card, and not a legit one. Multiple people on Reddit have come to find out that what they thought was a legit microSD card purchase might have been sold by an unsavory source, and not Amazon directly.
If you're experiencing the save issue, check out your microSD card. If you have the Samsung 256GB 100MB/s (U3) MicroSDXC EVO Select Memory Card, trace back your Amazon purchase and see where it came from.