iCloud Photo Library Image Count Problems

iCloud Photo Library has been stellar since I started using it shortly after it launched. I have suffered no data loss or corruption so far (I have other backups of course) and it’s been a joy to use. Once I upgraded both my Macs to macOS High Sierra, I finally flipped the switch on both my iPhone and iPad, turning on the new High Efficiency formats for both video and stills. Shortly after doing that, Photos for Mac and iOS started showing different counts of all the images in my library — they fluctuate every few days:

iMac (Download Originals to this Mac) — 33701 photos, 70 videos

MacBook Pro (Optimize Mac Storage) — 33701 photos, 70 videos

iPhone X (Optimize Storage) — 33703 photos, 70 videos

iPad Pro 10,5″ (Optimize Storage) — 33704 photos, 70 videos

iCloud.com — 33771 photos and videos (which I assume means 33701 photos and 70 videos)

This worries me. I still have 5 or 6 gigs of free space on my 200 GB plan so everything should work correctly. New content is added properly and syncing still functions as it should but what the hell are those additional photos on my iPhone and iPad?

I spoke with Apple Support and before they are willing to continue diagnosing the issue, they asked me to first log out and log back in to iCloud on every device. Since that would require at least 1-2 days of syncing (realistically 2-4), I’ll need to wait for a more opportune moment.