As a DM, it's ghosting for me. I often deal with repeat customers (players) who eagerly jump in when I start a new thing, only to see them barely participating after one or two months playing. It is honestly annoying because I have allocated significant time and attention working with them to make their characters fit into the story, even tailoring some elements in the plot to cater to their characters' backgrounds. 

And in the long run, it makes me restless; Maybe some new changes are needed? Maybe there was something in the narrative that they didn't like? And the worst part, it is hard to mend things when you have people completely gone from the radar, and you don't know why they are gone, and you can't ask them why.

It's understandable if things in real life prevent them from participating, but it becomes another if I see them online in my Discord server or returning once every two weeks to post memes without context. AT least keep us updated, a simple "sorry still busy this month" every once in a while would do just fine and take no more than 2 minutes of your time, or just withdraw from the RP altogether so I can focus on what is left, thought it's still annoying because I still have to deal with the marks that retiring character left, but at least it is better than having a character just idling in the middle of the road for the rest of the arc.