Adobe still can’t get XAVC levels right
This is the title of a post from Alister Chapman on XDCAM-User:
He adresses an issue or bug, that has been in Premiere for a long time: Levels are too high for XAVC S-Log material. This leads to clipping as well as inconsistencies with other color software like DaVinci, where the levels are correctly interpreted. The application of LUTs is especially problematic under these circumstances.
Please read Alister’s article for the details. This issue needs addressing.
It's pretty simple. S-Log clips are flagged as full range. Premiere recognises that but converts them to limited range, which "squashes" the levels.
All it would take is an option in the Modify Clip dialog to instruct whether the clips should be treated as the are, or override that.