I fixed the issue.
as you can see from the pics above, there is a lot of moisture and dirt getting in this compartment. Pics of the sub are included, and you can see how dirty it got in there in the 55 months of owning the car. It is no wonder these amps are failing, its a horrible place to place such sensitive electronics.
I followed this guys youtube vid to remove the subwoofer and amp:
Tesla mobile mechanic quoted me close to $700 to do this job, which included a new amp.
I bought a used amp off a EV junk yard:
Ingenext - EV Conversion, Used EV Parts, Tesla modifications
I got the amp for $180 vs the $360 Tesla wanted.
This is the old amplifier that is attached to the subwoofer enclosure.
If your model 3 is having speaker problems, or you lost your subwoofer bass, or you cannot do voice commands because the car recognizes half your words, then it is probably time for a amplifier replacement. I had all the symptoms above and made speech to text useless, only had front speakers as the rear would cut in and out and the sub was not functioning at all.
Super happy I got this fixed, and saved about $500 DIY.