I am working on a new pair of gloves for Medic, but the model itself is giving me a hard time.

https://i.imgur.com/Obcl2xJ.jpg

When I preview a lower detailed model, parts of it are strecthed infinately like the fingers in the screenshot. Since taking that one, I went through the model and adjusted the weights. It still glitches like so but worse. When I decided to put my lower detailed model into the main slot for a test, it does not stretch out.

Why is it doing that and what can I do to fix the issue?