Errors when editing an email template

Your software
My Mautic version is: 2.16.0
My PHP version is: 7.1.33

Your problem
My problem is: I create a Custom Mautic template. When I replace an image in the template, it appears distorted or flattened, and the color of the white link on the blue button is changed to orange.
Why does my template have this behavior?

Before replace the image:
Captura de pantalla 2020-03-10 a las 12.05.12

After replace the image:
Captura de pantalla 2020-03-10 a las 12.05.32