I believe you don't know the meaning of the term "end-to-end encryption". Obviously the application itself (and the phone) can see the text you put into it, because it has to display that text.

"End-to-end encrypted" means "from the moment the text leaves the phone, to the moment the text arrives at the recipient's phone, the text is encrypted such that no intermediate party can read it". You must of course trust or verify that the WhatsApp app isn't leaking your text, that the keyboard you are using isn't leaking your text, that Android or iOS or whatever isn't leaking your text, that you yourself aren't somehow taking unencrypted backups and you aren't using whatever unencrypted-backup features WhatsApp might make available, etc.