Reign of Guilds devs have addressed a recent XP exploit in a Steam blog post, plus their decision on their style of punishment.
Sea of Thieves had a pretty massive exploit that was discovered after the launch of Season 13 that will have repercussions for anyone who took advantage.
Ethyrial: Echoes of Yore, an MMORPG developed and published by Gellyberry Studios, has been in the spotlight recently for its ambitious attempts to correct their post-launch gameplay experience.