Happens in iOS and Android devices.
Using PasswordEchoOnEdit and ImhLowercaseOnly together deletes the first character when typing for the first time focus is gained. Example attached:

1. Build and run example
2. Click on the first QLineEdit which has PasswordEchoOnEdit and ImhLowercaseOnly
3. Type two characters -> first will be deleted after second is typed

This happens when the field is empty and focus is regained. If you empty the field, click on second QLineEdit and move back to first QLineEdit, then it will happen again.