First, the interface assumes the imperative mood. The text at the top of the screen should prompt the user for what to do. Secondly, the Russian-speaking person is much more familiar and understandable precisely the form of the word with the prefix "от", which is actually a little less literate. The wording "отсканировать" in QR context is used, for example, by Google: https://support.google.com/accounts/answer/9283368?hl=ru&co=GENIE.Platform%3DAndroid