If it’s PebbleTec and was installed by a licensed P-Tec installer, then they are on the hook for the warranty.
My opinion is it has been over-etch/exposed with too many acid washes and/or the water was too aggressive (low pH/TA/CH). My opinion - chip it out and redo it. That’s what I would push for assuming you still have some financial leverage.
My situation is similar to the OP except that my Pebble Tec pool is now over 4 years old. It was never a very good job from the beginning, but now there are some places in the pool that look like the OP's second photo. I agree with you that very likely that situation was mostly my own fault for putting too much acid in, trying to compensate for our alkalinic water here to keep the PH low in a vain attempt to keep the calcium off; I overdid it and I accept responsibility for it. However, that's not the main issue at the moment. The main issue now is that I finally had my boulders taken out of the pool set above a row of waterline tile (see other posts on that subject). However, doing that job also managed to damage the existing Pebble Tec so that guy recommended another guy to take out a few inches of the existing Pebble Tec and make the repair. Well, the repair itself was "okay" I guess but the repairman didn't protect the walls or floor of the pool very well. Yesterday we spent 2 hours cleaning out the floor and the junk they left in the drain, and now that everything is dry I can see that the bottom is now whitish with "streams" where clear water ran over the original and lots of streaks of white running down the walls -- as I said, it was never great, I made it worse, and this makes it intolerable.
The person who recommended this jackleg feels responsible and is coming tomorrow, says he can powerwash and acid wash the white away. Wife says that will be acceptable once the pool is filled again and I should just wait a few years before getting the whole pool replastered again. I don't agree even if. However, a full replaster (re-Pebble Tec) isn't needed except for aesthetics. The finish itself isn't that bad, the only thing that's genuinely bad is the ridiculous amounts of mottled colors, the gray-blue like in the OP's second picture, all the white stuff left over from the new repair, and the fact that the new repair itself isn't exactly the same shade. Hence I am wondering if it would be possible to deliberately STAIN the entire pool with a dark blue? I don't mean paint, I mean STAIN. If you can get stain on the Pebble Tec from rust and whatnot, why can't you deliberately stain the whole pool at the same time to give it a uniform color? Wouldn't he plaster part of the Pebble Tec take the stain without affecting the pebbles? That would definitely solve the mottled look it has. Anyone ever heard of this?
There are two takeaways for sure: First, never let the PB set boulders down into the water. None of this would have happened if the stupid boulders weren't absorbing water, flaking off into the pool and turning the sealant white. Second, even with a dedicated water softener for the automatic pool filler AND keeping the PH down (I was trying to keep it at 7.2 whereas it seems to naturally want 7.8), all I got was Pebble Tec damage and I still got calcium buildup (however, maybe there will be less calcium buildup now with the boulders no longer sitting in the water and flaking off all the time).
I had a pool when we lived in Florida and never had a bit of trouble with it. This pool in Las Vegas has been nothing BUT trouble.