Minecraft Version

1.20.1

Modloader

Forge

Modloader Version

47.4.0

Mantle Version

1.11.79

Tinkers' Construct Version

3.10.2.92

Describe your issue

Manually filling a casting tank waiting for fluid (to fill an item) will duplicate the fluid used to fill the container.

Confirmed with tanks, tools, buckets, potion bottles, and copper cans

Steps to reproduce

2025-08-10.12-17-54.mp4

1. Place empty fluid container in a casting tank
2. Fill the casting tank's tank with fluid of your choice
3. Profit

Crash Report

No response

Can you reproduce with just Tinkers?

Yes

Performance Enchancers

None of the above

Other mods

No response

Searched for known issues?

Checked pinned issues, Searched open issues, Searched closed issues, Checked the FAQ, Checked the in game books

Yeah, seems Forge is doing a dumb thing in the FluidTank implementation, where it returns a value from a global field instead of the local change. Means if something changes between the time the fluid stack is created and set, and the time its returned, for instance the callback for a fluid being modified, it returns the wrong value.

I have my own fluid tank impl that doesn't have this issue, guess I just switch to that for the casting tank.