LPG rigs are cleaner, safer and easier, but hydrocarbon fires are not specifically excluded - it's all down to risk.
Life or death usage extinguisher training where you must be able to use the correctly and experience that realistically still uses hydrocarbons, particularly motorsport - the perils (mainly to the trapped driver) of poor technique with powder on spill fires from crashes is graphically illustrated on footage in Youtube, mainly in the US, but also some Aussie stuff and a few notable F1 fatals over history - a gas rig is too forgiving.
A good relationship with the trade helps - some extinguishers we use are 'training stock' and I refill them, but a lot are 'scrap'* that we discharge and environmentally dispose of.
*not I hasten to add dangerous scrap but test due CO2 and also powders which are increasingly replaced with new after 5 years and not test discharged & refilled.