2007 Prius with recurring p0016 code. Could use advice

Prius 2007, 170k mi

So i was getting this p0016 code since the beginning of this year, i took it to a hybrid shop who seem to know Prius very well, and I believe what they did was they replaced my VVT valve, cleaned the throttle plate and the mass airflow sensor. The code went away for a while, and now its come back. Its possible that if I clear it, it will go away again, but idk. Now the engine is making a strange noise that i've never heard before -- as if its revving up to high rpm for short bursts even when at really low speed / cruising.

I know that this code indicates something with crankshaft / timing chain or something, but I guess this mechanic didn't seem to think that was the issue. I attached a few texts from this shop and I'm curious if you guys think this is sound advice. They seem pretty good and I'd like to take the car back to them, as I dont know any other hybrid mechanics in my area.

Could definitely use some advice on this one. I've been doing some simple maintenance and repairs on this car as a beginner (oil changes, coolant change, swapped my AC compressor) but I'm definitely not equipped to do any engine work. So thats why I'm looking to have a specialist figure this code out. I really just have no idea what is going on when it comes to the engine, "crankcase," etc.

Photos attached below: