Hostile Neural Networks 3.1.1
Minecraft 1.18.2
Forge 40.1.19

When a Loot Fabricator or Simulation Chamber's UI is opened, the first energy value displayed (the number X in "X/Y FE" that's shown when hovering over the energy bar) may come from uninitialized memory and is only updated next time the energy stored in the block updates.

For example, a fully-charged Simulation Chamber or one that's not gaining or losing power may appear to have a very high or very low (including negative) amount of FE stored within according to the GUI, but next time the energy stored updates, the actual value is sent to the client, overwriting the garbage data.

This should be fixed in Placebo 6.4.2. Technically that's not uninitialized memory but rather a copy of the lower 16 bits of the number being copied into the upper 16 bits.