Recently I have detected a huge drop in the traffic graphs.
If you type "quantum" in top right corner of the download report: https://download.opensuse.org/report/download?group=mirror you will see a daily traffic for recent days, which shows 60-90K redirects and 200-300M per day. Is it similar to what you see in your monitoring? How much traffic was before? We have some form of caching of small files if people use cdn.opensuse.org, but big files are still redirected to mirrors. Regarding poor coverage in the mirrors reports: it might happen for some (short) period of time after new releases happen. download.o.o now shows some better statistics about how fast new releases are propagated to mirrors (and next week it should show even better details), e.g. https://download.opensuse.org/app/project/2