On Android (Nexus 5, Android 6.0), when Battery Saver mode is turned on, the article-loading animation on the top becomes a very fast blink, as animation effects are removed from the system in that mode.
Interestingly, the general update/fetch animation does not seem to be affected.
Ooh, good catch. Haven't yet had much of a chance to play with BS mode in 6.0, so definitely do let us know if you find any other oddities with it turned on. I'll pop in a fix for the flickering shortly.