Unless anyone knows another reason for this impressive increase in comments? Seems to roughly coincide with Sync launching. If thats the case, just goes to show the importance of good third party apps.
Source: https://lemmy.fediverse.observer/dailystats
EDIT: Looks like a confusingly labeled graph and I think this is total comments. I have no idea why that spike could exist though.
Like @skye pointed out, I suspect it might indeed be based on region. I remember another thread where a user reported seeing Sync rated at 3 stars, whereas others reported 5 stars.
Ratings on play store are indeed localized (by region) but also by device type so it ensure that the ratings is relevant to your device (as the app experience can be extremely different on different devices running different Android version and/or Roms)
It also shows only ratings from the last of few last released versions in order to no skew the results with old versions of the app