From Software has been bringing down the ban hammer in the past 24 hours on Dark Souls 3 accounts suspected of cheating. However, some legitimate players have found themselves being banned.
Players suspected of cheating have been issued a message which reads “(Caution) YOU HAVE BEEN PENALIZED”. When this message appears the online experience has been disabled because the game has detected invalid data. This message will appear after an initial warning which reads “[CAUTION] INVALID GAME DATA DETECTED”.
It is impossible to know if some of the players are being banned unfairly but it appears that some players may be being penalised for picking up hacked items. Other software that’s also running on the PC may be triggering the detection system too, although this has not been 100% verified. Problems may arise from something as simple as, overlays, Logitech Software, or even Nvidia’s Shadowplay which was mentioned in the on-going Reddit thread. Corrupt saves are also a possibility.
A work-around is to use Steam Family Sharing and make a new account and share the games to the new account. You’ll have to start again so don’t copy any save data over. Not exactly ideal
It’s hard to pin this down to one single issue and there’s been no response yet from the developer.