Why does a cloud form around ice cream?

If I'm not mistaken, a similar effect happens near all sufficiently cold bodies: moisture from the air condenses and becomes visible when cooled from room temperature, a process similar to cloud formation. The reason it stops forming after some time, near ice cream or otherwise, is because the object gradually warms up to room temperature. If the foggy layer is still enough (e.g. we have liquid nitrogen in a thermally isolated jar and between the nitrogen and air there is a layer of condensed moisture), it actually serves as an insulator and somewhat prevents the sublimation/vapourising of the cold object.

In labs which use liquid nitrogen or helium for cooling, an even more awesome thing happens, which is somewhat of a level up to the ice cream fog: the moisture not only condenses, but solidifies and forms ice on the metallic sections of tubes and containers.

Water vapour from the air condensed and appear as white clouds. These white clouds diappear after some time because they gained heat and evaporated.

It is because of condensation of water vapour available in the air. BUT why there is not a cloud every time one has an icecream? that comes down to the dew point and wet temperature of the air in that room/place (aka ambient). Basically the amount of water vapour in the ambient air + the temperature of the ambient air dictates the presence or absence of the cloud.

Mist is tiny droplets of water hanging in the air. These droplets form when warmer water in the air is rapidly cooled, causing it to change from invisible gas to tiny visible water droplets. Mist often forms when warmer air over water suddenly encounters the cooler surface of land. -National Geographic Society

The cooler air around the ice cream met the warmer surrounding air and condensed into water vapour, hence a "cloud" (mist) forms over cold things(when taken out from the fridge or freezer).