In rec.aquaria.tech Nikki Casali wrote:
It's 31 degrees centigrade in my dining room where I keep my planted
aquarium. It's rather hot today! So at what temperature will my CO2
canister likely to "unload" its contents? According to the pressure
gauge, it's over 70 bar. I have just read that the critical temperature
is 31.6 degrees or 88.88 degrees F. Should I be worried?

It's essentially a gas.
It's not going to 'boil off' at one specific temperature.
I suspect that a blow-out plug will activate somewhere around 150C.