I tracked it down to 0.152.0, which led me here: Updates to Color Management in three.js r152
Setting THREE.ColorManagement.enabled = false; irons out most of the problems with the fire texture
Setting renderer.outputColorSpace = THREE.LinearSRGBColorSpace improves the grass texture but is too dark.
I’ll dig-in to the forum thread some more, now that I tracked down where this happened.