[impossible_cc]

Maybe there is more efficient method, but this should work

PHP Code:

#define STEAMID_CHARSTR_LENGTH 25

...(...)
{
    char steamid[STEAMID_CHARSTR_LENGTH];
    if(GetClientAuthId(client, AuthId_Steam2, steamid, sizeof(steamid))) 
    {
        DataPack pack;
        
        CreateDataTimer(2.0, saveBan, pack);
        
        for(int i = 0; i < STEAMID_CHARSTR_LENGTH; ++i)
        {
            pack.WriteCell(view_as<int>(steamid[i]));
        }
    }
}
public Action saveBan(Handle timer, DataPack pack) 
{
    pack.Reset();
    char steamid[STEAMID_CHARSTR_LENGTH];
    for(int i = 0; i < STEAMID_CHARSTR_LENGTH; ++i)
    {
        steamid[i] = view_as<char>(pack.ReadCell());
    }
    
    //done
}