Before this update, downloads in background and phone locked worked for me on Android after explicitly turning off battery optimization. But of course this was not an option on iOS.
Now with this update, on iOS background download seems to work for me as announced in the release notes, i.e. slow, but it does (and I don’t care in this case if it’s slow, and it may be inevitable because iOS is aggressive in managing background load). I.e., like this (but I didn’t confirm this on Android because I don’t use it anymore and it have worked in the past anyway, after changing the setting)
It’s needs at least 20% battery level for smart downloads to do anything, best is plugged in.