It’s not mind-reading. If you ask someone to turn on the kitchen light they’d just turn on the overhead light. That’s how it’s always worked till recently. If I wanted the kitchen lights (plural) turned on, that would perhaps be different. But the kitchen light is and has always been a singular light or set of lights.
you're giving her too much ability to reason things out.
People can figure stuff out using context, computers aren't good at that yet.
I have motorized shades, I have to tell siri "open the left window and right window." She doesn't know what to do with "open the left and right window." For a person, those 2 phrases are exactly the same.
you ask a person to turn on the light, they'll probably flip the closest switch on the wall. and chances are you subconsciously pointed at the proper switch when you asked.
If there's a bank of 4 switches, they'll probably ask you which switch they should flip.
in homekit, those would be 4 devices, and as far as homekit is concerned they're all exactly the same, A light with dimming. The only thing differentiating them is their names. People can make that name whatever they want.
The only way for siri to possibly figure out the main one, is order on the screen.
And what you think is THE light, might not be the same as someone else.
say my kitchen has 3 lights, and I've named them "round, square, and cabinet" which one is THE light?
Maybe siri kept hearing "light" when people were saying "lights." In those people's eyes, homekit was failing. since only one light was coming on. If enough of those people complained, apple might have fixed the "bug"
The only way to reliably fix this is to train yourself to use the full name.
either "bedroom overhead" or "bedroom ceiling"