This question is an exact duplicate of:
I noticed that the reputation shown for meta sites in the site list dropdown differs rather greatly from the main site reputation:
For example, there's a gap of ~2k on AU and AU meta (~1.5%), ~600 on U&L (~1.7%), and so on - the gap decreasing with total rep.
The differences are too large to be accounted for by recent changes in rep (~2k is my rep change on AU for this quarter so far), so simple caching is unlikely to be the cause.
Oddly, in meta sites, the rep shown in the top bar is correct (the screenshot above is taken from AU Meta), as is the rep in the user profile page, or that shown in posts by the user.
This screenshot was taken on Safari on macOS High Sierra, but the same thing was seen on Chrome on iOS and on Android.