Larian Studios Forums Baldur's Gate III Baldur's Gate III - Suggestions & Feedback The patch adjusted the frequency of damage taken from fire surfaces not mentioned in the patch notes

I don't imagine that surfaces are going to have saving throws, unless they are generated by very specific spells. They don't have a DC assigned to them so there's no saving throw to use. Individually giving every surface in the game a DC for a saving throw might not really be worth the effort, and might cause a great many things to bug out.

(And let's be real, if saving throws for most surfaces were possible, most enemies would coincidentally succeed the vast majority of the time.)