This mod doesn't add literal new items or change existing item stats, it merely reshuffles the vanilla loot of the game so you're more likely to try out existing gear you'd previously haven't used in a balanced matter.
The KOTOR Community Portal's modding guide is not new at all. It has existed for years. Previously it was hosted on the KotOR subreddit since as early as 2013. Unlike that modding guide on Steam, KOTOR Community Portal's modding guide involves active collaboration with modders, me included, so I can confidently vouch for the quality of KOTOR Community Portal's mod builds, and I cannot say the same about that modding guide on Steam at all.
The thing about installing a lot of KotOR mods is that you often cannot fix a problem with one particular mod by just removing the files of that mod. In fact, doing so likely just cause more problems to your game. Therefore, if you use a lot of mods, and you are encountering an issue that you do not know the source of the problem, the best solution is a complete reinstallation.