A response from NetSuite Support around this - apparently it's a known issue and there is no target date for this fix yet. This seems absolutely crazy to me / a very easy fix on their end 😮
"_As per checking, this behavior is a standard one. When exporting reports as CSV there will be a leading space on some of the items. There is a request logged for this._
As a workaround, our engineers suggest that you can export the report as Excel, then save CSV:
Alternate Solution:
1. Click on Export - Microsoft Excel button
2. On the Excel File > Click File > Save As
3. Select Save As Type = CSV (Comma delimited)(*.csv)
4. Click Save
_Currently, there is no target date as to when this particular feature will be released to Production. What I can do is attach this case to the said enhancement to add a vote for it to be implemented in the system. This would let our Product Team know that your company is also seeking this functionality. However, please understand that there is currently no target date as to when this will be added in NetSuite's future version._"