Blender Weight Paint Fix

I have already rigged my cartoon character with Rigify, but a few vertices still refuse to follow the bones correctly. The problem only shows up in certain poses, so the mesh looks perfect in one frame and then suddenly collapses when the lips move so main issue arear is mouth... (Budget: ₹600 - ₹1000 INR, Jobs: 3D Animation, 3D Art, 3D Modelling, 3D Rigging, Animation, Blender, Blender 3D, Character Design, Digital Art, Maya)