Stable update: Sub-layers; New 3D effects; Timeline audio tracks & more.
Narrowed it down to the "Share" standard built-in plugin. Build a blank project in r276, add "Share" object, export to app bundle / apk. Inspect AndroidManifest.xml with Android Studio, write external storage perm now exists.
Do the same steps in past Stable r268 and this permission doesn't exist for the "Share" object type.
Unfortunately removing the "Share" object from my actual Game Project didn't remove the permission though, so not sure other further built-in plugins are now causing this yet. I use no 3rd party.
You will have to post the issue on the github section, they don't care about issues raised on the comment section.