2008 Prius smell

Hello all,
I recently found a great deal on a low-mileage 2008 Prius, and I pulled the trigger. So far I’m really loving it! Except for one thing...
There is a very unpleasant smell in the car. It’s hard to describe, but it’s kind of a sweet, chemical, plastic-like smell. It reminds me slightly of cow manure. It’s bearable to ride In the car as I kind of forget about the smell, but it gets into clothes and linens and stays with me throughout the day. I’ve left the doors and windows open for a long time to hopefully get rid of it, and sprayed air freshener, but it always comes back.
At first I thought it could be some kind of product used to detail the car, but I feel like it should’ve gone away by now. I’ve checked to see if it’s coming from the leather seats, or the ac, or an offgasing dashboard or something, but none of these areas really have the smell. It seems strongest near the battery vent in the rear passenger-side seat.
I’ve seen a few older threads that mention this issue, but I’ve yet to find a more modern one, or any which offers a solution.
Has anybody else had this problem and discovered a way to fix it?
Any help is appreciated.
Thanks!

 

I’m pretty certain it’s not the carpet as they do not smell at all. The smell definitely comes from the battery area so this battery tube idea seems promising! Are there replacement tubes or something you can buy that won’t smell?

 

No old weather mats. The smell is definitely in the battery vent. What do these vent tubes look like? Has anyone tried and figured out if it’s okay to just remove them?