Canyon Endurace Al 6

Hi! I’m facing rear derailler cable replecment process in my Canyon Endurace Al 6 (bought in march 2023).

Just wondering if both cables (rear & front) should be placed in plastic tube in bottom bracket plastic cable guide? Only front derailler cable have plastic tube around it. I need to know if that’s how it should be or maybe original tubing around rear derailler cable disintegrated in those 3 years of riding 😬

Thanks for any help!