Heavily delayed push notifications

I rely on Google Play Services for push notifications. After one of the last few updates, I noticed these notifications are sometimes received on time, while other times they are delayed to as much as an hour and I can't quite figure out why.

I have given Unrestricted battery usage access to Play Services and Google Services Framework, yet they're delayed. I thought having Battery Saver enabled may have something to do with it so I turned it off but to no avail.

Any ideas?