When there is clear favoritism from GMs towards certain players.

You may have a character you really like. Maybe the player consistently has phenomenal posts. Maybe they posted something so funny you want to honor them in some way. But when it is evident that a GM has players they prefer over others and then it infects the roleplay experience, both IC and OOC, that can ruin an experience.

Part of this, I believe, stems from something happening outside of the roleplay. Instead of discussing the ordeal and seeing if it can be resolved, the players or GMs decide to ostracize that player or make the experience unenjoyable. Whether that's not letting them participate in a story arc or ignoring them, targeting their character in some way repeatedly, or giving spotlights to the same people over and over again.

I am not advocating for you to not have a character you like over another. I am saying that all your players should be given opportunities to shine and collaborate in the story in some way. We are here to write stories that are fun and enjoyable for everyone, but that's hard to do when it seems that one player is given more opportunities over another.

And please, resolve issues and do not let them fester. That kills RPs just as much as people not posting or updating on their own status as to whether they want to continue or not. And, as stated above, do so in private unless it is a group issue and then maybe do so in a group DM and not in the OOC or on the status bar.