Do you want to request a feature or report a bug?
bug

What is the current behavior?
In Android 5.1 (not 5.0 or other versions afaik);
When you write a word, delete it, and then write another word, the first character of the previously deleted word appears after the focus/cursor.

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem. You can use this jsfiddle to get started: https://jsfiddle.net/stopachka/m6z0xn4r/.

1. Visit https://facebook.github.io/draft-js/ on an Android 5.1 device (not 5.0 or 6.* or 7.*)
2. Enter non-whitespace characters, then press 'space'.
3. Delete all the characters entered.
4. Again enter non-whitespace characters, and press 'space'.
5. Notice that the first character of the characters you deleted earlier will appear right after the focus/cursor.

What is the expected behavior?
There should be no random extra character appearing after the cursor.

Which versions of Draft.js, and which browser / OS are affected by this issue? Did this work in previous versions of Draft.js?

Only Android 5.1 as far as I have been able to test. I don't have access to every version of Android yet, but have tested on Android 5.0, 6.0.1, and 7.1.1. None of those reproduce this bug, but 5.0 does have a similar bug related to autocomplete - see #1010.