Pic2 was seen after the Santa Rosa fires - not a new pic (visual memory anon).
Pic 1,2 appear to be hardwood trees, not redwoods. Pic 4 is in a residential area, not in the mountains where the ancient redwood groves are located. It appears to be a cedar (redwood family).
But yeah, you may be right, I'm not disputing your text because I really don't know, but if true, the pictures do not really illustrate it correctly.
It's true that if fire gets established inside a dead oak stump, say 3 feet in diameter (they do have huge oaks like that in parts of CA), the embers of that fire will keep burning, and burning, and burning, giving off no more than a tiny invisible plume of smoke from the burning roots, for weeks. Unless a strong wind comes and whips up the fire. Pic 3 reminds of that phenomenon.