This is a well known (long standing) issue. Documented in the code base in commit eea02be70ee37b845f2719b3c08e5baf4b6f51f6.

Countless intermittent sanitizer warnings can be attributed to it.
LogPrintf("Removing unusable blk?????.dat and rev?????.dat files for -reindex with -prune\n");
    fs::path blocksdir = GetBlocksDir();
    for (fs::directory_iterator it(blocksdir); it != fs::directory_iterator(); it++) {
        if (fs::is_regular_file(*it) &&
            it->path().filename().string().length() == 12 &&
            it->path().filename().string().substr(8,4) == ".dat")
        {
            if (it->path().filename().string().substr(0,3) == "blk")
                mapBlockFiles[it->path().filename().string().substr(3,5)] = it->path();
            else if (it->path().filename().string().substr(0,3) == "rev")
                remove(it->path());
        }
    }
    
    
    
    
    int nContigCounter = 0;
    for (const std::pair<const std::string, fs::path>& item : mapBlockFiles) {
        if (atoi(item.first) == nContigCounter) {
            nContigCounter++;
            continue;
        }
        remove(item.second);
    }
}
static void ThreadImport(std::vector<fs::path> vImportFiles)