I’ve definitely experienced ABS brakes before - i know the vibration you’re talking about (A Colorado native I’ve driven some rough terrain 
) The pedal was on the floor and I couldn’t press down at all. I was told that a possible theory was the ABS or traction control overriding the manual brakes - but either way it wasn’t working how it was supposed to be working.
They said that I don’t have a brake booster, just a brake module and it there are no leaks or moisture built up or anything. The brake stroke senor works perfectly fine as well. I had them do a fluid swap but they can’t do anything else. Should I pick it up? Take it to another dealership?
You should take it back to the same dealer when the warning lights come on, they are the ones familiar with your case. Going to another dealer after the Firestone shop has erased the fault codes will likely prove the same results.
The comments about the brake booster were assuming you had a Camry, not a Camry HV. BTW your hydraulic brake actuator costs $1800, I’m not saying there is something wrong with yours, rather this is something you don’t want a tire shop tampering with.
I have experienced this issue (not yet resolved). '07 camry hybrid. a very sudden change in breake behavior accompanied by the check vsc system, red BRAKE light, ABS light, skid light, tire pressure light, and the orange ((!)) (another ‘check brakes’ light). It is like the brake system decided that a) the regenerative brakes are not right, so they have been bypassed and b) the remaining hydrolic brakes have very little play. The peddle gets halfway to the floor before they begin to engage and then they engage very abruptly and sharply. Difference between the two, is mine is not periodic. it has been this way for the past 4 days. It began in snowy/slushy conditions but it was 65 degrees yesterday. I have plenty of brake fluid. It is 100% full. It is new as of last year (replaced by Toyota as part of their certified vehicle program).
I have read where if there is a failure in various components or communication between components of the electrical brakes (sensors, brake actuator, electronic control unit) , the electronic brakes will bypass the failing system and use what is left. In my case, I believe the regenerative breaks have become unusable. See the last page under “Fail-safe” in this document for the exact language: