While this may not be a bug, it does look visually odd. Ghosts in the sims 4 do not have feet, this is to simulate their floating better and probably takes visual inspiration from ghosts such as Casper the friendly ghost.
This is normally fine, but it looks very odd on a mermaid as it causes the ends of their tail to get cut off in ghost form.
Even if it is intended, the fins at the end missing looks very bad visually since it cuts off so abruptly.
A fix should be made so that the entire tail shows while in ghost form.
Edit By Crinrict: Added pack tag to title.