So I'm going with the nuclear option here and getting the whole back glass replaced by Tesla to reset to no tint.
I actually had the tint redone once already for other issues, and I think the experience from doing that made my tinter hesitant to take it off, even though I offered to pay. I tried reaching out to someone else in my area but did not get a response as well.
As pretty as the back glass is, I wish it was a bit more practical in terms of design from a maintenance perspective (like the hard to reach corners and such).
There's a cost, and though not cheap, it was less than what I had in mind, so I'm going to move forward with it. Lesson ($$$) learned...
Again, this is on me, as I know others don't mind those lines, but it bothers me enough, especially since my previous car did not have this issue due to a variety of factors (tint type, glass angle, defroster line thickness, etc.)