The NO_CRC32 flag indicates that the file header or chunk has no checksums computed for it, and is expected to be fixed at 0. Files with this flag set can be found in the system32\winevt\Logs folder on new-ish Windows Insider builds. Logs that have been exported via wevtutil.exe have the flag removed and the checksums computed as part of the export.
The NO_CRC32 flag indicates that the file header or chunk has no checksums computed for it, and is expected to be fixed at 0. Files with this flag set can be found in the system32\winevt\Logs folder on new-ish Windows Insider builds. Logs that have been exported via wevtutil.exe have the flag removed and the checksums computed as part of the export.