Yes, this is a behavior that is in accordance with the HomeKit Accessory Protocol (my description was linked above by @crxporter). The post @crxporter is referring to is this one.
Being the dev of the Homebridge plugin I can confirm, that I fixed this issue very early on (not having a proxy item for every light in my home was one of the main reasons I developed this plugin). I am currently using a 250ms delay, however this surely can be reduced a bit, just didn’t came around yet to test the minimum value required.
Either implement a proxy item and stick to your current setup or give my implementation a spin (additionally the dev of the official openHAB HomeKit plugin is currently working on the plugin, therefore it might be possible that he is also implementing some fix for this behavior).