You' re probably cutting the tube too short and stretching it to the breaking point. You just need lengthen the tubing to where there is barely enough tension on the rubber to align the peep. Making it too short will torque the string and mess up your accuracy and make the bow harder to tune.

Even then the rubber will fatigue after awhile, or break down from UV radiation, and it will break. The tubing also flaps around on the shot and makes a lot of noise.

Best fix is to get rid of it altogether, get a peep like the Fetcher TruPeep or Shurz-a-Peep 2X2 and learn how to orient the peep in your string so it comes up square to your eye at full draw.

Or you can try the old style Shurz-a-Peep that splits the string into 3 parts and always comes back square. Only problem I' ve had with that style is there always seems to be one strand of that string in front of my eye.