This question came from @AlphonseAmala on Twitter:
@Sitecore need replacement function for StringUtil.GetSizeString(long size) - it's not available in Sitecore.Kernel version 14 (Sitecore 9.3 migration) issue. Need help
When upgrading to Sitecore Experience Platform 9.3, what change should be made to replace GetSizeString(long size)?