My settings for Easy Days do not sync across devices. I set them on one laptop, sync, and open Anki on another laptop but they do not stay consistent.
There is added confusion as this is the only setting in the Deck Options that does not sync (so if, for some reason, it is not meant to sync, it is therefore still confusing and I’d recommend annotating that in the tool tips or in the documentation).
From my prospective as a user who reviews mostly on iOS, I should be able to set the settings on my laptop and then have those Easy Days consistently set on the iOS app (as well as all other locations).
FWIW I experienced this problem before trying to make a change to these settings in the iOS Anki app (two different Mac laptops would not stay in sync). However, once I used the iOS app to make a change to the Easy Day settings, it now stays in sync across all three devices, even if the change originates from the laptops.