How did you ask Tesla to make this change? Got some aftermarket 20" wheels as well, not too critical for me though as I had the 19" Gemini wheels before.
Make an appointment through Tesla app. Schedule Service > Accessories > Tire Swap.
Do mobile service, select the earliest time. Tell them you got 20 inch wheels, you did a swap. Use a pic of induction wheels (since they're denying aftermarket for some reason).
They'll push it through.
But in your case, you're right, the rated range for 19" and 20" is the same at 315mi so it won't make a difference for you.
Swapping the sensors without dismounting is easy on higher profile tires like the S’s 45/19’s or X’s 45/20’s but on the Y’s very low profile and wide 275/35R21’s it gets much more difficult. I wouldn’t expect a shop to fool around with very wide and low profile tires. I own a couple tire machines and if you are careful it’s not a big deal to pop off the tire. I would however say that the car would relearn the new sensor and the shop wasn’t familiar because many people have already been swapping Model Y wheels without issues, that’s definitely more "easy peasy"
The sensors do relearn but the car still thinks it has the original size wheel. Model 3s give the users the ability to change wheel sizes in their software but Model Ys don't have that option yet.
Even when I swapped the wheels snd tires, my car still thought I had the 21" Uberturbines with a rated 280 miles range so my data was a bit skewed, in a positive way. My car thought I am driving at over 100% in efficiency when in reality I was driving 80-85% in efficiency with the 20" wheels on a epa rating of 280miles instead of 315miles.
I think most people swap the wheels won't care too much about the data if they're not looking at the numbers. The car won't throw errors, just the range and efficiency data number won't be accurate for them until they can change to their wheel size on their car.