I've confirmed this bug with multiple people. A person sees their ship health differently than other people see it. The difference can be as large as 4%. I'm basing health reporting off of sector list, which as far as I know is not affected by plugins.

Yes, we quantize health visibility sent over the network to 16 levels, where local health of a person viewing their own ship is not quantized at all and has full resolution. The game has always been like this.

that explains that. cool.