Skoda Yeti electric seat problem

A discharged battery could mess with the electrics. The car seats draw a fair bit of power, especially if they are heated or have multiple seat motors for fine seat adjustment. Have you noticed any other electrical issues, like the infotainment system acting up or the engine taking longer to crank?

I haven't seen any other electrical problems, but the car hasn't been used much lately. Could a few weeks of sitting cause the battery to drain enough to affect just one system, like the car seats?

It's quite possible. Modern cars are very sensitive to voltage drops. A slightly weak battery can cause all sorts of seemingly unrelated errors. If the car's been sitting, the battery might have discharged enough to affect the seat motors, since they require a good amount of current. Before tearing into the seat itself, I'd get the battery tested or charged. If the battery is OK, take it to a workshop. There might be a deeper issue with the car seats.

It was the battery! A new battery and a reset of the error memory got everything working again. Cost 290€. Thanks for the tip!