What is this exactly on my brand new Model Y?

[Brian-MS90D]

That would be the response from any automobile manufacturer / dealership after that much time had passed.

 

[Dexion]

I ordered a black MYLR and when it came time to deliver, I noticed the same marks in almost the same location and I rejected the delivery, partially because of those streaks as well as a small dime-sized dent on the passenger door that I just wasn't confident would be fixed by a SC. This isn't exactly helpful to you but it seems like it did come from the factory like that.

 

[robjg63]

It really looks like something or someone has scuffed something against the car. Maybe some branches or shrubs.
I am a little surprised that you only noticed it after 3 weeks - I looked at my car a lot when I first got it.
It seems like maybe they werent there when you got the car?

From the photos it looks like they are only on the surface - Have you actually tried anything on them - Maybe a little car wax on a microfibre cloth?
I would try that on a small patch and see what happens - not exactly diffiicult or expensive to test.

 

[EV_Dad]

Again, those lines are visible only in direct sunlight. If I park it under a shade its not visible.

Sounds like a factory paint defect underneath the clear coat. I hope not. But either way, based on my experience with a similar issue, I'd take it elsewhere because Tesla service centers and their contractors are hopeless at detailing and repainting.

I reported a large defect on my frunk hood immediately. For over a year they detailed, repainted, repainted again, and then ordered an entirely new hood painted by their own collission center. Each time it had similar paint defects, plus the last time they dented the new hood. Throughout the process, no matter how patient and polite I was, I had to navigate endless incompetence and disrespect.

At least the paint guy at your service center admits his people can't fix it. Sounds like he's ready to quit, lol. Take it to a good detailer, and if the problem does turn out to be under the clear coat then I say either just live with it (and accept that travel and parking lots will exact a toll on your paint anyway) or take it to a paint shop with a good reputation.

 

[chevyguy2021]

It simply looks like buffer trails. Not a big deal and should polish right out. You only notice this is the sun due to the reflection of the clear coat. Get a good detailer to polish these out and apply a ceramic coating and your are good to go.