Power BI automatically normalizing text casing during data load

Hi KumbharM​,
Thanks for reaching out to the Microsoft Fabric Community forum.

Yes, the behavior described is documented for Power BI.
The Power BI engine that stores and queries data is case insensitive, so it treats text values that differ only by capitalization as the same value. In contrast, Power Query is case sensitive, so it can display the casing as stored in the source before the data is loaded into the Power BI model.

Microsoft also explains that, when data is loaded, the Power BI engine evaluates rows from top to bottom and maintains a dictionary of unique text values. When it encounters values that differ only by case, they are treated as the same value and the existing variation is referenced. Therefore, the capitalization displayed in the model can correspond to the first variation encountered during loading.

This explains the behavior in the example where PunE, Pune, pune, and PUNE are loaded and subsequently displayed using the casing of the first occurrence.

For a connector scenario, once the values are loaded into the Power BI engine, case-only variations are treated as the same value. The Microsoft documentation specifically recommends, for DirectQuery with a case-sensitive data source, normalizing casing in the source query or in Power Query Editor.

For more details, please refer to the below Official Microsoft Documentation:
Data types in Power BI - Power BI | Microsoft Learn
DirectQuery in Power BI: When to Use, Limitations, Alternatives - Power BI | Microsoft Learn

I hope this helps. Please feel free to reach out if you have any further questions.
Thank you.