Texas has 8.25% but New Mexico is 5.125%
Sunland Park, NM (which is part of El Paso, TX metro are has an additional city+county tax of 2.125% so the taxes are the same as in Texas (the numbers may be slightly off, but the final tax rate is very close to Texas)
There’s an option to prefer fuel saving routes, which are worse most of the time. This was a kinda recent chance and it is enabled by default, try to disable it and see if it helps