I've had two of my tamed/trusting mobs die by sitting in a campfire. It wouldn't be too big of a deal if they weren't rare mobs that required me to go very far to get them.

The first mob to sit in a campfire was my tamed parrot, and the second was my trusting fox.

I ran some tests in my creative world, and in an enclosed 7x7 space, a fox will sit in a fire on average about every 15 seconds, and die in 30 seconds, a parrot is about the same. Both of the instances where this happened in a survival setting I was in an open space and close by to a campfire. (One in a taiga village with my parrot, the other with my fox at my home base)

I've noticed the same problem with Wandering Traders/Villagers and llamas in sweetberry bushes, they'll walk into them and just stand there and do nothing about being hurt.