I'm not a pro but it looks weird or off to me. Maybe a pro will jump in since this comment will bump it up in the queue.

It looks weird..You don't need tile there

I don't care for the look of the tiled side wall. I know some do it that way, but it always look awkward to me. I think it should just be on the back wall....

There should not be a "gap" between the counter and wall. Any tiny (less than 1/8") gap can be filled with caulk. If the countertop was cut incorrectly or not laser cut, then there could be a gap issue. You don't need tile on the side wall. I would have it removed and the wall smoothed then painted. If there is a gap, then they need to recut the countertop. I have the same situation in my kitchen in meeting the wall - just caulk, the backsplash ended at the end wall.

We cut ours at an angle from the top cabinet down to a 4" back splash, looks good. Once again, things like this stand out until all the decor is in then it vanishes.

No, this looks like they are covering up a gap. It doesn't look good and will continue to bother you if you don't get it fixed now.

Tell the contractor to take off the tile and get a piece of counter that fits to the wall

The only thing I hate more than a sidesplash is a sidesplash attached to a cabinet. Be grateful they did not do that too. Yes, make them fix it.