>>28625060
Nothing really went "wrong" but my 4runner's stock rear cargo vent was missing its rubber flaps (likely got disintegrated after 25+ years) that would have prevented dust from entering the rear cargo so I replaced it with a third party vent as it does not use rubber flaps to prevent dust/debris from entering my cargo.
Found out the hard way when I went off roading last month and went to clean up my 4runner and saw all the dust near my rear wheel where the vent was.