Wetness under carpet

Like a 'wetness protection program'?
Where's the truck from?
Otherwise, I was going to say flood damage but looks like OP got it figured out.

 

It's certified used with a 100,000 mile powertrain, but coverage for that issue is not covered. I have 68,000 miles on it now.

 

On the awkward locations that can cause strange things to happen note, if you’re in a damp environment and always park in the same spot, moss will grow in your northern most facing vehicle light. Also, it’s always a good idea to keep leaves and debris out of the hood jams and around your ventilation intakes at the base of the windshield, for the interior. Over time it can turn into mold.

 

I had the same problem. Here’s my thread I started just in case it could help someone. You can read the whole first part if ya want but if ya skip to the end, I updated with a Toyota tech found an unsealed hole lower in the firewall and water would splash in and caused the water under the carpet and that stinky foot smell from the carpet. Good luck!

https://www.tacomaworld.com/threads/water-under-carpet-potential-solution.773476/