Welcome - although you did not say if you were a prostate cancer patient, some of us do know more than we would like about catheters.
If you had some damage to the urethra, as we do when the prostate is removed (it is severed, then reattached), the bleeding is on the outside of the catheter tube, so it drains around the tube whenever there is any stress, or when you have bladder spasms. It continues until there is sufficient healing.
Blood on the inside of the catheter comes from the bladder. In my case the Foley kept poking me, and causing irritation, thus bleeding.
However, the correct "answer" is - call your doctor, and ask if what you are seeing is expected.