Where does Oxygen come from in KO2 reaction with CO2?
Yes, the oxygen indeed comes from the decomposition of potassium superoxide ($\ce{K2O}$) but the other decomposition product is potassium peroxide ($\ce{K2O2}$) and not potassium monoxide($\ce{K2O}$).(Here)

$$\ce{2KO2 -&gt;[290°C, vacuum] K2O2 + O2~~~~~~~~~~(1)}$$
Now, this potassium peroxide reacts with carbon dioxide to form potassium carbonate and oxygen.(Here)

$$\ce{2K2O2 + 2CO2 → 2K2CO3 + O2~~~~~~~(2)}$$

Adding $\ce{(1)\times2}$ and $\ce{(2)}$, we get full reaction. (Here)


  $$\ce{4KO2 + 2CO2 → 2K2CO3 + 3O2}$$




If reaction proceeds in aqueous medium, it gives potassium hydrocarbonate and oxygen.(Here)

$$\ce{4KO2 + 4CO2 + 2H2O → 4KHCO3 + 3O2}$$