At first I thought it was a bad translation from Chinese to English, but it turns out that many data-sheets of kWh power meters mention a maximum altitude, usually below 2 or 3 km.
For example:
What exactly is the reason for the height (altitude) restriction?
Electronic components are rated for altitude because:
I'm guessing the EE SE would crush this one out of the park with real-world examples.
Expanding item 2 in Tiger Guy's good answer I'd say it's definitely about dielectric strength.
Electronic devices manufacturing standards (e.g. IEC62368-1) define creepage and clearance distances according to nominal voltage, basic or reinforced isolation need, materials and categories, aka environment where the device is supposed to be used.
The required distances are finally up-scaled according to maximum allowed altitude.
Infact Paschen's law relates dielectric withstand with atmospheric pressure.
So good manufacturers specify the choices done when designing.
One possible factor is that convection cooling of the components becomes less effective at high altitudes. Thinner air doesn't carry heat away as well.
Here's a good answer on electronics.stackexchange
Briefly: air is ionized by being hit by fast electrons. When there is less air, the electrons move farther between collisions, and become faster and more energetic before hitting an air molecule.
This also creates the counter-intuitive effect that it requires more voltage to get an arc as items get very close: if the electrons don't have enough space to accelerate, they don't get enough energy to ionize air molecules.
At very high altitudes (the edge of space) there isn't any air at all, and arcing becomes less of a problem.
