It's not a light leak because that would show up brighter on the image. There is also a definite splashy aspect to the fault which screams "liquid issues". Not sure what the bright bits are; they could be the edge rails on the spiral, dribbling a little extra developer onto the film at that point; if I'm right then those white bars will have a close pitch at one end of the roll and a coarser pitch at the other end.

Also, overfilling the tank is really bad idea. You need a big quantity of air in the lid for agitation purposes. There must be enough air to completely rearrange all of the developer in the tank when you invert it; if you overfill the tank then you only have a little bubble and inversion doesn't cause any real agitation.

I never had mine ride up, but then I only used a Paterson for about 100 rolls before I moved onto a Jobo, and my spirals were pretty tight on the centre core. I'm guessing they include the locator-clip for a reason.