I have this message. But I still show 32gB remaining. Why is that?

Hi, please be aware that you've started using chargeable services while roaming. Any calls, texts, or data will not come out of your standard UK allowances and will cost between 30p and £15.00 per MB. To keep track of your spending or manage your bill cap, simply log in to the iD Mobile app. For more details on out of plan charges, visit idmobile.co.uk/roaming