The answer to 'why is my leak repair' is that there are several common causes for a leaky repair, including poor installation, incorrect pipe materials, or damage to the repaired area. Symptoms may include dripping water, wet spots around the repair, or even water damage to nearby surfaces. To fix the issue, you'll need to first identify the source of the leak and then take the appropriate steps to re-seal or replace the repair.
If the leak is minor and you're comfortable working with plumbing, you may be able to DIY the repair. However, for more complex or extensive leaks, it's best to call in a professional plumber who can properly diagnose and fix the problem to prevent further water damage.