Known defect, presumably from 2002 model year and beyond. Lexus reportedly will supply up to $250 for a "cover" if you complain long enough and care to do so. TL;DR, you're going to have to fix this yourself by taking the dash out, stripping it and re-coating it.
There is no real way to cover the problem. You can either replace the dash with a brand new 02-05, or replace it with a used 2001, or take it out and strip it all down and repaint. I personally replaced mine with a used 2001.