Simplified Twitter does not collect, store nor send any information about the user neither the device.
It runs a small JavaScript code inside *.twitter.com website to make it behave like it does on smaller screens.
Feel free to open an issue at https://github.com/brunolemos/simplified-twitter.
If you find any bug, please contribute by opening an issue or sending a pull request with the fix.
Updated: September 07th, 2019.