There appears to be a TODO item that's been left in the code. It fills the log at a worryingly high speed, leading to the logs becoming useless once in-game. Log viewers that display while the game is open will then cause a noticeable performance impact or fail to even display the log due to this error.

This is what shows in the log, constantly:
[02Jul2024 16:54:43.938] [Thread-20/ERROR] [EMI/]: [EMI] TODO implement JEMI support for fluids again

You can find it in the logs posted here with limited context:
#577 (comment)

Arch loom finally updated so I was only able to get to this today, resolved in 1.1.9