This is one of those "well actuallys" battles that has been lost a long, long time ago my photographic friend.

Yes, "RAW" itself isn't a format like TXT or an acronym like JPEG, but in practice RAW appears alongside other all-caps names like JPG, DNG, TIFF, etc. in menus and documentation and so the industry has mostly converged on writing it RAW for consistency.

Fujifilm writes "RAW": https://fujifilm-dsc.com/en/manual/x100vi/connections/raw/

Nikon writes "RAW": https://onlinemanual.nikonimglib.com/zf/en/raw_processing_59...

Canon writes "RAW": https://www.usa.canon.com/learning/training-articles/trainin...

Leica writes "RAW": https://leica-camera.com/sites/default/files/pm-73002-Leica-...

Even Adobe writes "RAW": https://www.adobe.com/creativecloud/file-types/image/raw.htm...

Descriptively yours,