Hi hang-single,

Thanks for the screenshots. It shows me something but not the why. I firmly believe that some results can be caused perhaps by several influences. Just guessing is not my MO. (If I would guess then: your Height Scale is too large, I would wonder if that fixes it)
https://stcineversityprod02.blob.core.windows.net/$web/Cineversity_Forum_Support/2023_Clips_DRS/20230917_RS3518_Keller_Legacy.mp4

Please share a project folder with related textures for those kinds of questions. (Reduced to the problem, zipped and please via Dropbox, [Google, Apple, Adobe, Wetransfer is OK too, anything else hasn't been cleared [security].)

The improvements around version 3.5.11 or 3.5.12 for Normal mapping can be ignored and set to Legacy. Here is also to mention the Keller Algorithmus; see link. If Legacy works better, then it seems you found your setup.

Please have a look here:
https://help.maxon.net/r3d/cinema/en-us/#html/Bump+Map.html#LegacyNormalMapTechnique
https://help.maxon.net/r3d/katana/en-us/Content/html/System+-+Advanced.html

I will try to get more information into the manual about when and how to use it.

All the best