Some funky stretching going on in character animation Well, first of all, I saw many posts about stretching, but mostly they are about unproperly vertex painting and in those other posts you can see the stretching directly in the viewport, but my case is a little different, I double-checked all the vertex weights and my stretching just appears in a couple of frames from the final render(so the stretching appears in one frame and disappears in the next one), not visible in the viewport

Thanks in advance.
Problem fixed... False alarm!!!, I double even triple checked my mesh weights, (but only in my main mesh, since the stretching looks gray), and I have the eyes and shoes as a separate mesh, all these three parented to my armature, finally I double-checked the eyes and they were parented to the armature with an orangy tone, not totally red, after I weight painted them in full red the problem is fixed... Anyway, the weird thing is that I was not able to see the stretching in the viewports, maybe that would have given me a clue of where the problem was.