Is the genie in the bottle experiment a physical or chemical change/reaction?

Chemical reaction.

Step-by-step explanation:

In the experiment, a catalyst is added to concentrated hydrogen peroxide.

The hydrogen peroxide decomposes rapidly, according to the equation

2H₂O₂ (ℓ) ⟶ 2H₂O (ℓ) + O₂ (g)

New substances are formed, and old ones disappear, so this is a chemical reaction.

The reaction also releases a large amount of heat.

The rapidly-expanding oxygen gas caries with it droplets of water and hydrogen peroxide (and probably some steam, as well).

The visual effect is like a genie escaping from its bottle.