Newbie here, trying to model a character having weird issues when trying to slim down the legs

Trying to slim it down
No effects on the leg.
When I try to slim down the leg, it doesn’t actually slim down the leg. It seems like the vertices I made are inside the cube which is suppose to be the leg, but I don’t see any vertices that allows me to manipulate the actual leg as all the apparent vertices seems to be “inside” it?

I deleted the vertices and made new loops and for some reason now it’s working. But I would still be curious to know why it wasn’t working the first time.

Hej welcome, i guess you used the mirror modifier on a mesh that already was having geometry on both halfs ( i just should have geom on one side for that) Then they get doubled on each side and it leads to that geom doubling you had.

I believe that is indeed what happened. Thank you!