There are no statistics to back up this statement. All we know is that both EVs and ICE car’s spontaneously combust on rare occasions. There are examples of both here:
https://normantaylor.com/blog/which-cars-catch-fire-the-most...What’s interesting to me is that most people talk about NMC batteries in EVs, but from what I can tell LFP batteries should be safer and are becoming more popular. Would be good to see if there are stats to back this up.