I’ve got an iPhone 14 Plus (oversized) and it can be finicky in my ‘23 Sierra with the same charging pad. I initially had a lot of the same issues, but I raised up the armrest and tried placing it down multiple times in top-up and top-down orientation until I found the best fit and also to get a feel for how to center it. I noticed that if you were just a fraction of an inch off to one side, it would try to charge but throw the yellow triangle. After 2 months, I have gotten much better at placing it in the right spot without looking and it works much better.
With all the different sized phones and cases, it’s really difficult to create a one-size-fits-all wireless charger in a car. Think about it this way — your wireless charger is either model-specific (a la Apple MagSafe) or it’s a flat pad on a desk or table (and even those can be finicky if you don’t get it perfectly centered). It’s much more difficult in the confined space of a vehicle to get one that fits everything.