I figured it out. The problem is the number in the filename. I changed it from RalSurcharge2 to RalSurchargeTwo, now it works...

If it still not works, then it can be because the file `events.xml` is in the wrong folder. I wonder why it ever worked for me, normally it has to be in `MODULE/etc/webapi_rest`

https://magento.stackexchange.com/a/189439/66769