ReferenceError: fetch is not defined  (at backend) ???

**Describe the bug**
I made app in NodeJS. I've tested it in browser and everything works. After packing it into .apk my backend throws this error, when trying to use fetch().
Why??
I don't understand it, I'm using nodeJS v20.  FetchAPI was implemented in v18. Does compiled backend in Android uses another nodeJS version than the app was created with? 

**Expected behavior**
no error.


