I did do custom & beta, 5.7.14 is the version used for $UNAME, it built fine besides not finding the modules directory with "-Unraid"kept as localversion
if the 'UNAME' variable is changed for another kernel version having 'unraid' as part of 'CONFIG_LOCALVERSION', it breaks building bzmodules as it looks for the version without 'unraid' in the version string, removing 'unraid' from 'CONFIG_LOCALVERSION' fixes the issue