Thanks for the replies.
The issue appears in the frames that are underexposed. So there are some frames from the roll that do not show this pattern, but the distinguishing factor appears to be the exposure. It could be a scanner issue, but my setup is well tested and has not produced issues like this before. So, I thought it might be development.
I prewet by 4 30 sec. washes. As far as I know, the Jobo was level.