Looking at https://oss-fuzz.com/ for swift-protobuf, the Total Coverage link resolves to https://storage.googleapis.com/oss-fuzz-coverage/swift-protobuf/reports/20250908/linux/report.html. So it seems there hasn't been any coverage data collected since then.
Looking at history for oss-fuzz, there might have been a move to llvm 22 right after that that might be part of the reason, but I'm not sure. I don't see any changes made to the swift-protobuf setup specific to that time frame. And the other reports still seem like they may be working.