Don't show my E-Signature when i open my file

There is an error in the way that "Assinado digitalmente" has been added to each page of the document.

For example on page 1: That symbol has been added to the page by additionally showing a form XObject FFT0 which in turn shows a form XObject F0 which then shows a bitmap image Im1. The error is in the form XObject F0:

q
  1 0 0 1 2.8346 3.8346 cm
  0.1867 0 0 0.1867 0 0.0934 cm
  q
    167 0 0 166 0 0 cm
    /Im1 Do
  Q
Q
Q

As you can see, there is a closing Q (restore-graphics-state) too many.

Some viewers ignore this kind of error. But while this error is indeed easy to ignore technically, it often indicates that somewhere there is a missing q (save-graphics-state) before that extra Q, and that the content between that missing q and the final extra Q  is displayed incorrectly (at the wrong position, at the wrong scale, in wrong colors, ...). Thus, it is sensible that Acrobat does not show that broken XObject but warn instead.

You should inform the producer of that PDF about the error in their PDFs and ask them for a copy without it.