I have (or had) the same flashlight, with the same holster, same problem, and coincidentally, with the exact same carabiner to hold it. You sure that's not my keychain?

The best thing I can recommend is ditch the holster and put a small keyring directly on the flashlight. The holster just adds more bulk and doesn't really serve much purpose. I was using the lanyard to connect it to the carabiner at first, but I eventually got rid of the lanyard too because it was always getting tangled up. Now I like it much better, less bulk and more secure