Reproduction Steps:
Well, I just put down some of the Mermaid-themed furniture in my new farm area and... well, the water fountain looks more like an oil fountain
Repro Rate:
It happens all the time. I haven't found a way to fix it...
Game Platform: PC (Steam)
Game Version: 1.1-1225
Input Mode: Controller, though I don't think it's relevant
#Furniture particles look weird underwater
elder vapor
Save File and screenshot of the issue: added a pic of the same fountain above ground for comparison, one is a water fountain and the other is an oil fountain!