The kitchen scale mystery (moved, two scales don't work)

yirara

I don't get it! I moved internationally recently and thought my kitchenscale broke down, being stuffed in a very full suitcase. Maybe too much pressure. Anyway, for periods it would not stay on zero but switch between 28 and 0 constantly, and the same would happen if I weighed something with a range of about 30-40.

I bought a new one and was initially happy. Then the same happened again a day later. Usually this scale works in the morning, but in the evening when I'm about to cook things go wrong and the weight flickers between up to 40 grams, sometimes even when I switch it on.

Both are just very simple digital scales. No wifi, no special functionality. I still wonder if there's something in my flat that might influence it. The worktop is a completely flat stone. Can't make up my mind whether it's natural or artificial. Tried different locations, also away from the huge Smeg range. Underfloor heating that only runs in the evening. Though it's usually done running when i start cooking. Heat of course still radiates into the room.

Any suggestions?