I have a left and right Nautical Blue Front Stock Fenders for sale - and the associated fender liners and flares off a 2014 SR5.
$175 each fender+Flare
Make an offer on the liners.
Located in Irvine, CA - not much way of shipping these efficiently.
It should be plastic riveted in place if it has one.
The ones shipped to California will have them in place. And yes, it is a significant restriction on airflow. And yes, a California smog tech will look to see if it’s there.
That’s the carbon trap. It’s a California required smog device and is usually checked visually by a California Smog tech. Outside California your mileage may vary as to whether to ever noticed that it’s gone.