Page Twitter officer of BANDAI NAMCO Entertainment US recently announced that ONE PUNCH MAN: A HERO NOBODY KNOWS they will cease their service from February 28, 2022:
One Punch Man: A Hero Nobody Knows multiplayer servers will sunset on February 28, 2022. All offline game modes, along with online 1vs1 game matches, will still be available for play.
Thank you for your understanding and continued support.
– Bandai Namco US (@BandaiNamcoUS) July 20, 2021
Exactly one year ago, July 2020, the game received the last two additional playable characters Garou is Watchdog Man.
ONE PUNCH MAN: A HERO NOBODY KNOWS is available on PlayStation 4, Xbox One is PC.
Source: BANDAI NAMCO Entertainment Street Siliconera