I accidentally washed my AirPods Pro in machine

Replacement, most likely.

Try to dry it first and not using it at the moment. Place it where the water will come out. You can also try the rice method. If all else fail, contact Apple Support for a replacement.

Rice... is not a good choice.

Good way to get rice into spots that it might not be easy to get the rice out, too.

For drying other devices, Apple recommends directing a breeze of dry air.

Having washed a few bits of electronics over the years, I’m less than hopeful drying will work.

And immersion in wash water and soap tends to lead to corrosion.