Prompt: "Keeping the glass and the hand behind the glass the same, please change only the three brown candies in the glass into green, yellow, red, and orange candies. Make no other changes. Change the reflection to remove the brown candy too." Seed was 1070229954903864, but your setup is probably too different for that to help.
It seems like Gemini 2.5 Flash was the only model that successfully removed the reflections...it should get some points for that!
By the way, this is what I got from Kontext after just a couple of tries: https://i.imgur.com/J4LwkVI.png
Prompt: "Keeping the glass and the hand behind the glass the same, please change only the three brown candies in the glass into green, yellow, red, and orange candies. Make no other changes. Change the reflection to remove the brown candy too." Seed was 1070229954903864, but your setup is probably too different for that to help.
It seems like Gemini 2.5 Flash was the only model that successfully removed the reflections...it should get some points for that!